There are several versions of practical pistol out there. Of main two, IDPA and USPSA, I think that IDPA is the easier of the two to start in. The courses of fire are generally easier, and there is normally less movement.
In USPSA, there are several divisions. Some use race holsters that are more just frames that barely hold the gun on your belt and others use standard belt holsters.
There are a couple of other flavors of practical pistol: ICORE (revolvers only), Steel Challenge (steel targets only, very little movement), and GSSF (Glocks only, no movement, not drawing from the holster) are some.
A primer on IDA is available here:
http://www.richmondhotshots.com/docs...ter%20Info.pdf