Oh man. I once wrote a whole series of articles on just this topic. I will try to crank out a list of a few tips.
1. Whenever possible relate directly with the Lama NOT the Dharma center. This is huge and probably the most important piece of advice. Everyone that is a permenant fixture at a Dharma center is priding themselves on how close they are to Rinpoche X. To protect this status, they will try to control your access to Rinpoche X and even tell you what Rinpoche X would say if he were here. There are a few dharma centers that are not festering sores of political nonsense but sadly, it is very few.
To accomplish this you may need to be brazen and just walk up to the Lama with a serious question and ask for a private session. You may need to be sneaky and show up when you are not supposed to be there. You may want to offer your services to the Rinpoche directly (NEVER through their representatives at the center).
The best path is often through the translator. Translators are hated by the people in the Dharma center because no matter how much of an patrol or servant they are they cannot have the relationship that the translator has. Not only will the translator enjoy being genuinely appreciated but they will have the secrets bits of the sadhanas that no one else gets.
2. Most people in the Dharma Scene are not serious practitioners of any kind. Ignore them. Most people into Buddhism are simply into feeling exotic by decorating themselves and their homes in eastern crap. Others are into it as a "path of blessings", they run around the world on an endless summer going to teachings that they have had hundreds of times. For them the practice IS getting the teachings. If the very affluent people in the inner circle seem to treat you like a rube because you don't have the opportunity to go to the yearly month long retreats in France before hopping over to Martika for the 3 week retreat, and then back to Manhattan for the summer teachings, you can ignore them or make them feel like idiots by asking a genuine practice related question. These people almost invariably know diddly-squat despite having a million teachings.
This is not just a western thing. In fact many Tibetans and Taiwanese are even bigger offenders at this, only being interested in the chin-lop (magic power) conferred at empowerments. If you ever go to a Tibetan teaching in a very heavily Chinese area you will see 300 people at the empowerment and about 12 at the instruction for how to do the practice.
3. Even amongst the serious practitioners you must realize that if you are interested primarily in magic, you are in it for exactly the opposite of why 90% of the serious practitioner are in it. Most people in the west are interested in Meditation, Ethics, Buddhist Psychology, and just plain old religion. When they don't completely ignore it they tend to treat the shamanic stuff and wilder Tantric stuff as either quaint superstition, or something that they actually wish was not there at all.
If you tell these folks that you are using Kurukulla to help you get promoted at work or get laid at a club, or that you are using Simhamukha to reverse psychic harm back to the sender, they will think you are cracked. They will tell you that only the Lamas are capable of such feats and that anyway the lower actions are a trap. If you actually get to talk to a Lama in private about these things, they will usually be delighted to discuss them at length.
4. The Lamas agree on NOTHING. When people say "All the Lamas say.." or "Tibetan Buddhists all say..." they are talking out of their ass. There was one weekend that a certain teaching was being given by Chagdud Tulku on the west coast and by Lama Wangdor on the East Coast. Chagdud considered the teaching should be restricted to only those who have completed at least their 100,000 prostrations from the Ngondro and would cost $300. Lama Wangdor considered that the teaching should be open to anyone that paid $20 to get into the Carpet shop in Tribecca where he was teaching. Same teaching. If one Lama says one thing, another will say another. There is no party line, especially amongst the more heterodox schools like the Nyingma, Bon, and Kagyu.
5. Despite what some people will tell you very Tantric practice has two aims. The first is the supreme siddhi of enlightenment mchog gi dngos-grub. The second is the use of lower siddhis thun-mong gi dngos-grub. These are mostly divided into four categories ‘phrin-las bzhi. Nabbing a piece from one of my own Gurus here, these are:
"White magic or Shantika-karma (zhi-ba’i ‘phrin-las) has the function of calming and pacifying conditions and healing. White Tara is an example of a deity that specifically has this white function.
Yellow Magic or Paushtika-karma (rgyas-pa’i phrin-las) has the function of increasing wealth, prosperity, abundance, merit, knowledge, and so on. Vasundahara and Jambhala are examples of deities with these functions. Hence they are yellow in color.
Red Magic or Vashya-karma (dbang gi phrin-las) has the function of bringing people under one’s power, of enchanting, bewitching, attracting, subjugating, magnetizing them. This is the primary function of Kurukulla and hence her red color.
Black Magic or Raudra-karma (drag-po’i phrin-las) has the function of destroying evil and obstructions to the spiritual path. This is the specific function of many wrathful manifestations such as the Dakini Simhamukha who is dark blue in color.
These four functions are allotted to the four gates of the mandala palace, namely, the white or pacifying function in the east, the yellow or increasing function in the south, the red or enchanting function in the west, and the black or destroying function in the north. With each of these four magical functions there exists an elaborate system of correspondences."
Later in the article, John Notes:
A text like the Arya Tara Kurukulla Kalpa contains many ritual practices of lower magic to accomplish specific goals, for example:
1. amulets for enchanting and bringing others under one’s power,
2. spells to frighten away poisonous snakes,
3. methods for a dissatisfied wife to subjugate her husband,
4. amulets for protection from evil spirits and bad luck,
5. spells for acquiring wealth and gaining power,
6. the use of cowrie shells in divination and ritual,
7. divinations to find a treasure,
8. methods for walking on water,
9. methods to avoid getting gray hair,
10. cures for frigidity and impotence.
In one Kurukulla Sadhana found in the Sadhanamala(No. 72), there occurs a list of eight great siddhis or magical powers acquired through her practice:
1. Khadga-siddhi (ral-gri), the power to be invincible in battle with a sword (khadga);
2. Anjana-siddhi (mig-rtsi), the power to remove ordinary lack of sight by using a magical ointment that enables the user to see Devas, Nagas, and other spirits;
3. Padalepa-siddhi (rkang-pa’i byug-pa), the power to be swift of foot by using a magical ointment that, when applied to the feet, allows the user to run with incredible swiftness;
4. Antardhana-siddhi (mi snang-bar ‘gyur-ba), the power to become invisible;
5. Rasayana-siddhi (bcud-len), the power of rejuvenation and long life through obtaining the elixir of life by way of an alchemical process;
6. Khechara-siddhi (mkha’-spyod), the power to levitate or to fly through the sky;
7. Bhuchara-siddhi (zhing-spyod), the power to move freely through the earth, mountains, and solid walls; and
8. Patala-siddhi (sa-‘og), the power to have command over the spirits of the underworld (patala).
You can read the rest of this essay by Lama Vajranatha (John Myrdhin Reynolds) here: http://vajranatha.com/teaching/Kurukulla.htm
6. Apart from just the action mantras included in many Sadhanas, there are sometimes entire spell books dedicated to particular Yidams, Guru's, and Dakinis. There is also MO, or divination practice. There are also the higher magics associated with the Dzog Rim or perfection stage practices. These include but are not limited to developing illusory bodies, inner heat yogas, Body transference rites, etc.
7. Approach it from its own base according to its own path. Chaos Magic, Hermetic work, Witchcraft, Santeria, and all other practices are not the base from which you should interpret Tibetan Magic. Only Tibetan magic is. Most of the early translators made lots of errors, some of which persist to this day (tulpas) based on their Theosophical interpretations.
Realize that Tibet has spent as much time on magic and spirituality over the last 1200 years as we have on science and technology. Take a few years and learn it on its own turf. Then later you can compare, contrast, and combine to your hearts content because you will know what the hell you are talking about. I had a personal mentor and it took me over five years to establish the kind of competency I am talking about.
8. Last bit of advice: when you have gotten your introductory teachings from the Lamas that visit where you live, go to Nepal or India, even if it is only for a few months. What do Chokyi Trichen, Chagdud Tulku, Lopon Tenzin namdak, Kunzang Dorje, Khenpo Namdrol, Ngakpa Jampa, Lama Dawa, Khenpo Tenpa Yundrung, and Choknyi Rinpoche all have in common? They are all Lamas that I received teachings from while hanging out in their bedrooms. Nuff said.
I know that I will get this question: "why a few months and not a couple weeks?". Two reasons. First is cost. The plane ticket will cost you more than it takes to live there for a month. It is a very cost effective trip if when you get there you find somewhere that you can pay rent by the month and eat what the locals eat. Even if you do splurge, it will cost you a fraction of what it costs here. The second is simply that it will take you two weeks to a month to even figure out what the hell is going on. The teachings there are all advertized by word of mouth and occasionally a flier up on a restaurant wall. If you haven't ever done third world traveling before, that alone will take a while to get used to. In Nepal, you haven't been there long enough unless you have gotten your chest infection.