Are There Advantages?
Pyschic vampires have to deal with the constant urge to feed for the rest of their lives. It can be a nuisance at times, and if not feeding properly, a psi can become very ill. There have even been reports of psi's dying when shutting their body off from outside energy and allow themselves to drain fully. Along with feeding, there are also problems with sunlight, being attacked by other empaths (I've been told psi energy is very appealing to many out in the world of empaths), drinking anything with citric acid (can eat away at your stomach easily, we cannot digest such juices easily), and many other life-long symptoms that come with the territory.
But beyond these disadvantages are abilities psi's can use thanks to their psychic perseption/empathy. The following are the abilities I have heard of. All those with a * next to them indicates that they are abilities which are good for starters. Some are even vital to the progression of your abilities. They are also ones which I have personally practiced and accomplished. All others are merely what I have read about and have yet to practice them.

Sheilding*
Sheilding is VITAL for psychic vampires. It is what allows us to "filter" energy when we take it in. Without a sheild in place, it is easy to take on the emotions of the subject you're feeding from. Sheilding can also act as a defense from attacks from others who may try to feed off of you.
To sheild, you want to feel your aura, your natural energy found outside of you. Become familiar with it. Then, once able to sense it well, WILL it to condense and harden. A good way to picture it is like a space suit, or a scuba diver's suit, only not skin tight. This is known as a base sheild. It is made completely of your own energy. In this condensed and hardened form, it makes entry from outside sources (other psi's and empaths) very difficult.
One note: empaths can become familiar with your aura, and can "tune" their attempts of entry to get in. To prevent this during an attack, you can change the base sheild by "tuning" it as well. One excellent way of picturing it visually is by changing the color of your aura. If it's blue, and you feel the attacker getting through, change it to red, or orange, etc. Do NOT change it to black. Though this prevents outside access, it also prevents you from feeding through your sheild at all. White is then, obviously, much more helpful, for it blocks outside access well, while allowing you to feed through the sheild with ease.

Linking*
One way of getting to know someone is through linking. Linking is used to transfer energy for any reason; ie. feeding, scanning, etc. This can be done by any two empaths, psi or not. To establish a link, you need only focus on the other's energy and tap into it. Feel it and become familiar with it. Then, depending on what your goal is, you can draw in the energy and/or push energy from you to the other. If you do both, it creates a constant flow of each other's energy, creating an almost cleansing feeling. I personally find it very theraputic and relaxing, and quite exciting the first couple of times.

Skelpting*
Skelpting is basically the same as linking, except that the link made is much stronger. The feel, or rush, of skelpting is that of linking ten fold. It's a fantastic feeling. It's more or less done personally as a form of intamacy (you know who you are). To accomplish this, it requires mental projection along with the link. Once a link is established, you must project to the other and exchange energy there. It allows for more freedom, because your projection can evolve into anything you prefer (raw energy, a human form, etc.).

 Astral/Mental Projection*
Astral and mental projection are things which, though not necessary for psi's, can be accomodating in a lot of situations. The main difference between the two is the numbers of people involved, and the convience.
Astral: This form of projection requires more control of your empathic abilities and much more patience. First timers will need to be well meditated, with little or no outside noise at all. Be in a position that is comfortable to you. It is suggested that your arms and legs are not crossed, but rather at your sides (I'll normally sit in a large recliner or something along those lines). Once in a state of deep meditation, you must project yourself, your energy and sense of being, out of your body. It helps to picture this as a twin body, though any form can be used (animal, vegetable, mineral... you get the idea). You can project yourself in many ways. I personally find picturing my entity above me, and then try to focus on what being up there would feel like, look like, etc. Soon enough, I find myself actually up there. If you can do this, congratulations, you're projected. You can WILL yourself to go wherever you want, see whomever you want, etc. Don't be surprised if your senses aren't like they are in normal living. You may not see well, or not see at all. Many things in the empathic field is done through feel. It should be noted that astrally projecting is dangerous for psi-vamps. There are many entities out in the astral world that love our "taste", and would quickly feed off of you or worse at the drop of a hat.
Mental: Mental projection can be referred to as the "private chat" of projections. It is easier, because you are not projecting your entire self, merely your energy and thought. You and the person you wish to see/interact with focus on a dense fog (this is one of the ways, works best for me) and then see the other coming through the fog to you. When both do this effectively, you can eventually get a clearer and clearer image of the other. From here, you are free to exchange energy, or simply get a feel for the other. This requires less effort, and can be done in a relatively aware state with little meditation (when compared to astral projection).

Scanning*
Psi-vamps are able to differentiate between people based on the feel or look of their aura/energy. This is hard at first, but can be accomplished over time. When feeding, you will notice a difference between an angry person and a happy one. Furthermore, you will be able to sense a fellow psi-vamp from a regular human (nil). Each has a different feel to them. You need not feed to sense the difference, merely feel their aura (like you would when ready to feed). After doing this with different people, you will be able to tell the difference.