Your Community
One of the best sources of both information and help is your community of fellow musicians and industry people. While not always free from it's own source of stress (politics and gossip), other musicians can help dealing with problems and finding solutions. It also helps to have a community of like minded people who are pretty much going through the same type of things you are. Just getting together with fellow working musicians on a regular basis can ease some stress and allow you to get some steam off your shoulders.It helps to vocalize your problems even though you may not be actually doing something about it (at the time, hopefully you will do something about it). Other parts of your community include various support groups (not necessarily for musicians), your PRO, musician organizations. musicians' writing and recording groups, forums, various local music interest groups, and any people you have working with your band (agents, managers, lawyers etc.)
Getting Organized
A great way to deal with stress is to eliminate it right from the beginning. Being organized is helps kill stress by not having to worry about missing appointments, knowing that details are taken care of, and that you are following your plan. If anything comes up, you're more likely able to deal with it effectively since you have a system in place. If you have any new ideas or things to do, being organized allows you to deal with it and make sure something gets done. As a working musician, things are going to pop up and you have to be organized to deal with them. Plus, being organized allows you to follow your goals with focus a lot easier. Research some of the 'getting things done' programs. You'll end up tweaking it and making it your own but it has to be something that you do on a regular basis.
Planning
Always take time to plan. It's important that you take time on a regular basis to make plans and just as important, to review these often. Planning eliminates stress because it gives you some control over what direction you're heading; even though this is never clear cut and requires constant updating. If you take the time to plan on a regular basis, you feel good about your career and tend to feel that you are in control and heading in the right direction.
Keeping Notes
Most of the time you'll end up getting the best ideas at the most inopportune time. Always keeping notes helps keep all of these ideas organized. Most musicians have a workbook of some sort (i.e. lyrics, music ideas, career ideas, etc.). It's good to keep all of these in the same place so that you can come back them and reexamine them at a later date. Also, if you have a notebook with all of your ideas, it's easier to come back to them and add notes and develop these further.
Getting Help
If it gets to the point where you're unable to perform effectively, you may want to seek some help. The first place that you may want to go is your music community. Most musicians are aware of and have gone through something similar at one time. They may have first hand experience on how to deal with the problem you're going through. There are also numerous other places that musicians can go for help of all sorts. Most of these may not be music specific but helpful otherwise. There are support groups for public speaking (for performance issues), networking, planning, business practices (all for help with career development), depression, and creativity groups to name a few. Even these don't necessarily deal with musicians specifically, a lot of the problems that you may be having with stress could be helped by one of these groups.
Onstage Jitters
One thing that some performers have a hard time with is onstage jitters. Everybody gets a little nervous before going onstage but for some people, it's a huge deal. Symptoms range from jittery nerves, stomach sickness to debilitating headaches. Even some well-known seasoned, professional performers go through these on a regular basis. There are a couple of ways to deal with this. First off, one of the best ways is to simply be really prepared. It takes a load off your mind when you know that you've done everything you can to make your performance shine through. Make sure you have your set down. If you've gone through the entire set and are familiar with all of the material, then that's one thing that can ease your mind. Another thing that can help is having a pre-performance ritual. A lot of performers have a ritual that they go through before each performance. This would include some breathing exercises, warm-ups and scales, going through a tune or two, and maybe some meditation. Some performers don't like to talk to too many people before a show whereas others don't like eating too soon before a performance. Another big helper is to get to the gig early. Once you've been there a while, it gives time for your nerves to settle down and get into the vibe. Besides getting tons of experience onstage, these are the best for trying to get over your performance jitters.
Bad Practices
There are numerous things that musicians do on a regular basis that creates stress. One of the worst is simply trying to deal with all of your issues by yourself. Musicians spend a lot of time alone and are usually alone in managing their career. Whenever things get tough instead of going deeper inside of yourself, try reaching out and trying to find some solutions elsewhere. It takes a lot of stress off your mind when you know that there are people just like you out there that may be going through the exact same things. Like mentioned before, just talking to someone about these things may ease the stress tremendously. Along the lines of some good practices to do before a show, there are a number that are bad. Of course not being prepared is a big source of tension. Getting to the gig late with no set up time is another source of stress. Not warming up is also a bad idea especially if you're one of these people (like me) that needs a good warm up before they're 100% effective.
Dealing With It
Everybody has to deal with stress. Musicians and artists arguably have their own issues to deal with. Start off right by getting organized and stay organized. This way you have some control over where you are heading. Update and check your plans regularly so you know that you're getting things done and haven't gone off course. Create good practices as far as your work schedule, doing shows and anything else that may be causing you stress. Try to communicate with people on a regular basis. Your music community can be a source of help but just keeping touch with people, family, friends and fans helps keep your head in the right place. Most of all, know that if you're doing all of these things that when you lay your head down at the end of the day, you've done everything you can to move your music career in the right direction. At the end of the day this is music, and it should be fun!