The Tinder algorithm is a rather complicated thing to be honest; it considers so much when making matches... Some of the things that have to be taken into account are:
- Sexual preference
- Common interests
- Common friends
It has been suggested that when you first use Tinder, the first few people you are shown are the most attractive; this is probably to make sure you continue to use the app.
Also, the app will look at how many people you swipe to the left, if you are too picky not only will that make a difference to how many matches you get, it may mean that you get less choice in future.
I feel that a lot is also based on how many messages you reply to, if you ignore people you stop getting so many matches, or people to choose from.
It's impossible to know for sure how the algorithm for Tinder works as the developers won't divulge this for obvious reasons, but this is based on how I see it after using it for a month or so.