There are no rules, and your right about getting experience. You get experience by doing. So just go and do it. Learn to think for yourself and resist the temptation to take shortcuts or the easy path. Only you can decide what you mix should sound like. Try everything and every option you have to mix levels and pan instruments. Commit and save that mix to a file, cassette, DAT, CD-R, whatever. Make dozens of these different mixes and make notes on what you did. Then listen to them over and over and make notes again on what you like and don't about each one. Go back and mix again. Repeat until you either get exactly what you want or are as close as you think you will ever get, then come back after a period of time, say a week, month or more and then try to mix it again and see if get any closer. This is how you gain experience.
Take it in small steps. Don't worry about eq or effects until after you think you've mastered the basics of working with levels and pan. Start with mixing only the levels and no pan, mix everything in mono. Don't worry about pan or stereo until after you have graduated mono. Keep in mind that this is an on-going learning process that is going to take many weeks, many months and many years to accomplish.