Skating is basically an individual sport, and activities during most practice sessions are pretty unstructured. It is important to know though, that some basic rules must be observed for safety, and to ensure that everyone can make effective use of their ice time. Your rink/club will have its own set of rules, and you should be sure to know and follow them. This section outlines some basic concepts which are common to most clubs.
First and foremost is courtesy. It is essential to respect the rights of other skaters and be constantly aware of who is around you. If you seem to be surrounded by skaters of significantly greater or lesser skills, be especially careful! Strive to avoid collisions!
In most rinks, the skater who is "on program" (who's music is playing) has the right of way at all times, and other skaters are expected to give them free maneuvering room (In many clubs, these persons will be given bright vests or belts to wear, to make them more noticeable). Second in priority are those skaters who are currently in lessons with their pro. Always yield to these skaters as well.
Because of the nature of the Lutz jump, it is most commonly performed in the 10:00 and 4:00 corners of the rink (unless you have a lot of clockwise jumpers in your club). These corners are informally called the "Lutz Corners", and can usually be identified by the unusually large concentration of divots in the ice. Strive to avoid long-term practice activities in these corners, and try to be especially aware of your surroundings when you are in them. Remember that the approach to a Lutz is long and blind. The skater doing the Lutz is not likely to see you.
When you are practicing elements like camel spins and back spirals be especially aware of the danger your exposed blade poses to other skaters. Recognize that once you've started the element it will be hard for you to see those around you. Take a good look at your expected "space" before you start the element, and abort it if it looks like you could cause a problem.
If you've got pairs skaters at your rink, and they are practicing on the same session as you, be aware that two skaters moving together take up more room than one, and generally can't react as nimbly or quickly as a single skater. If they are doing lifts, be aware that once a lift is started, the skaters are pretty much committed to their "path", and that getting into that path can be dangerous for both you and them.
If you should fall, get up quickly. Remember that the other skaters will have a much harder time seeing you when you are down low on the ice. Don't stay there any longer than you have to. While falling, remember to keep your fingers away from your blades. And learn to fall properly so that you can protect your head as much as possible. Learn to keep "loose" when you fall and this will help you to avoid breaking things.
If you see someone else is that has fallen and may be injured, don't just drag them off without being certain that doing so won't hurt them further. If you suspect that someone is seriously hurt, the best thing to do is, 1) have someone stand "guard" over them to make sure that other skaters avoid collisions with them, and 2) get a qualified adult to come and help them. A blanket or warmup jacket/sweatshirt laid over them might help to keep them warmer while waiting for qualified help to arrive.
As you skate more, you'll get to the point where you'll recognize that a practice session has a certain "rhythm" to it. People tend to do pretty "expectable" or "predictable" things, and you can usually pretty much guess where somebody else is going, based on what they're doing when you see them (the normal approaches to each jump or spin are pretty recognizable). If you're a "wrong way" skater (clockwise jumper) be aware that other skaters will probably guess wrong about your intentions pretty often. If you have clockwise jumpers in your rink, try to recognize them and adjust your expectations accordingly. Try not to skate or behave in a way that would surprise other skaters. If you're standing near the boards, don't enter the flow of skaters without checking to make sure you're not going to get into someone else's way.
Refrain from standing around and visiting on the ice. This wastes expensive ice and presents an additional hazard for other skaters to avoid.