Nowadays there is a wide variety of available flight simulator software. Fortunately, most of it can be broken down into two or three categories, in addition to the general flight sims, which will be of help to those who want to explore the field of flight simulator software, but don't have a clue where to begin.
The first thing to do, before you begin your exploration of flight simulator software, is to think about why you are interested in it: do you have dreams of action packed mid-air battles? or do you want to see what it is like to be a commercial pilots? or, maybe, do you want to travel back in time to a more glorious past and pick sides in one of the epic air-battlefields of the 20th century. Whatever you are looking for, you can use it to narrow down the sort of flight simulator software that is suited for you.
If you are into more action with your gaming, then the sort of flight simulator software that is suited for you is the combat flight simulator. These come in many flavors, from the less intricate to the over-the-top in depth, but all will allow you to lock onto some enemy jet or fire your machine gun at enemy turrets. But if you are more into more everyday flying, you might want to look into a different flight simulator software program, such as the Microsoft Flight Simulator series or the Flight Unlimited series.
A different sort of flight simulator software is the historic simulator. It allows you to choose a period of history (generally, or at least the most popular being, WWI and WWII or the Korean War) and then choose a side. This vein of flight simulator software achieves varying levels of success. Those that are best have widely different play experiences for each model of aircraft. So, a Japanese Zero needs a different flying technique than a Spitfire.
The final thing to remember about flight simulator software is that it is for fun. If you are not having fun with your flight simulator, then you are using it wrong. So choose one that is suited for you, and then kick back and relax.