1. FS - essentially, you ask what's on the menu.
2. looks of girls - just like the girls you pass by walking down the street, the girls vary a lot in terms of age, weight, boobs, etc. read the reviews under the MP section to get an idea as to who is who.
3. App't - I never do, but that's because I want what I want and I want it now. Thus, app'ts don't work for me. If you are planning on seeing a girl who works solo, such as Oshi or Pam, you are well advised to make one as it can be very difficult to hook up otherwise. If you want to roll with the moment then simply stop into an MP and see who's available (that's what I do). But sometimes even when there's multiple girls working they can all be occupied. If you have someone specific in mind, make an app't. BUT, if you make an appointment either show up or cancel well in advance if you have to. No one likes a no-show and it reflects poorly on fellow pooners.
Hope that helps.