This is a good question and one that impacts just about all vampires.
I am a very well developed psychic and empathic vampire. I have developed
techinques over the years for sheilding myself from unwanted energy as a
psychic vampire who relies on this energy as my main source. I am also a
pranic feeder, however my pranic sources are not what they once were and I
am very discriminating on my donors..
Sheilding for the vampire refers to the blocking of unwanted energy for the
vampire. This is an important element in a vampire's health. As energy
feeders, vampires are greatly affected by other people's energy and some of
this energy can be detrimental. This is especially true with psychic
vampirism where many kinds of energy are "absorbed". There then is "bad"
forms of energy such as what may be found in the emotions of others and the
mental probes of other vampires. Learning sheilding techniques is then
paramount to any psychic vampire's health. There have been many methods
introduced to help with sheilding development. It is generally recognized
that use of your imagination combined with focusing skills can help here.
Some vampires have had success with using light sources such as candles or
focusing on one specific object in the room with you and "blocking" out
other distractions around you. Here you must concentrate on the energy of
the candle or other object of your attention and "break" the effect and
impact of the unwanted energy sources. This takes time to develop, but can
be done with a little effort, especially if you have some psychic ability.
These are just suggested behavorial learning techniques and what may work
for one may not for another. Generally, these approaches are a foundation to
developing your own sheilding abilities.
Once sheilding skills are well developed and the ability is acquired to
separate out that emotional energy that is desired, can psychic feeding off
of emotional energy be successful. As are all souls, vamps are bombarded by
emotional energy constantly when around other people, it is the vamp who is
sensitive to that energy and so becomes it. This is what truely separates
emapthic vamps from ordinary people, ie. the ability to readily absorb any
emotional energy nearby. So with the postive comes the negative and the
"pain". It is the well skilled vamp that can sheild the pain of negative
emotions  and energy probes of other vampires so to avoid them. This of
course does not mean some of this energy will get thru. I as a well
developed empathic vamp feel the pain of negative emotional energy every day
when around other people, but it is kept at a minimum with my sheildingability.