Find the CC forums. Scroll to the older threads on any Forum and read them. Order some self defense books by well known authors: Suarez, Pincus, Ayoob, etc. Subscribe to some firearms magazines that focus on handguns, read the holster and CC articles. Internet Tactical Ninja Warriors spend more time in their mothers basement posting opinions on the Forums than they do reading, learning, and practicing their skills, take all Internet opinions with a few grains of salt (including mine).
You will buy some holsters that don't really work for you, it happens to everyone. Resell them on the Buy, Sell, Trade section of this Forum.
Cheap holsters are cheap for a reason, buy good ones.