Photographing sports is dictated by how the game is played, true also, who is playing.
If you are not familiar with a sport you will have to adjust to shooting it. How much will depend on a number of factors including your experience level, the sport, and the level of play. Being familiar with a sport doesn’t mean seeing it on TV, it can give you some idea, but not the full picture.
The main thing on my mind when approaching a new sport is how to achieve the best relative isolation of my subject(s). What direction can the action take and where do I need to be to capitalize on it? Knowing the sport (and your subjects role) will help you anticipate where to be positioned.
Two terms (as I use them) I’ll further define are “subject” and “relative isolation.” By “subject” I mean the player (or specific thing) you want to capture. Sometimes you’re tasked with capturing a specific player which is wonderful because sticking with one player tends to be easy. Most times you’re documenting the team or game which just means you have to pay more attention.
When I say “relative isolation” I mean that in your photo the viewer will clearly know who the subject is. This can mean seeing their entire body while others in the image are only partially shown (if at all) or that they dominate so much of the frame there can be no doubt. Nine times out of ten this means they have (or are about to have) possession of (or involvement with) the ball, puck, or other potential scoring device.
In (most) sports such as soccer, basketball, and even baseball the meat of the game often happens at a fixed point like the goal or home plate. In football and rugby there is an “end zone” but it’s such a wide area you’ll be challenged to isolate a spot where things will culminate. Scoring is terrific to capture but when you’re just starting off don’t be overly concerned with it (in theory if you’re following the ball you’ll be in the neighborhood when it happens anyway.)
Lots of great things happen aside from scoring. Sometimes these great things involve collisions or contact of some kind. Look for the game within the game (even away from the ball.) Two players battling for position can make for great photos. The intensity of a point guard coming off the pick or the stiff arming of a would be tackler are good examples of the game inside the game. Keep in mind too that great (photographic) things happen off the field and when the ball is out of play. Emotion is often expressed after the whistle blows or off the court/field/pitch/ice.
One last thing regarding the level of play. If you feel you’re destined to be photographing sports for a living, starting with lower levels of play is a great way to cut your teeth. The action is much slower and it’s much easier to find your way into a high school game than a professional game. Aside from the Olympics I’ve photographed every level of basketball to some extent. It is remarkable how different the games are played at each level. The transition from college to the pros and even the difference between the women’s and men’s games take some adjustments.