Since you asked about a "solo" set up:
I have used almost every major brand of gear over the last 30 years of performing and have found out these few simple hints:
1)Portability is vital if you move around alot. Try to limit your rig to one keyboard or controller. Lots of stages don't have the room for a "concert" setup. Lots of venues don't even HAVE stages!
2)Keep the pieces small so you can add to the sound system as needed. I would never bring in a pair of 15" speaker cabinets if I was playing in someones living room! A better plan is to use smaller speakers and bring a powered subwoofer for larger jobs. That way you can always get a good sound - no matter how large or how small.
3)Be aware of the "drunk factor" if you plan to work bars and weddings. Make sure youe rig is stable and "BUMP PROOF" nothing gets me like a bump in the teeth with a microphone, because someone lost their balance on the dance floor! For that reason, I never use a mic stand that isn't attatched to my keyboard stand. It can't move too much that way. Better protection for your gums and quicker set up time with a smaller footprint on stage.
4)Versitility - do you use sequences? Drum patterns? CD's? MD's? All of the above? make sure you have a neat way to organize all your performance media within reach. Don't make it possible for a box of disks to fall over and cause you to stop the show to "pick up" the band!
5) Lastly - make sure YOU CAN HEAR! A good moniter is vital to your health and the performance. It is very rare that the main sound source is positioned at a convenient location for the artist. Most times the best spot for a sound system is very inappropriate to hear from stage. That's why you need a good way to moniter your performance. Don't rely on room acoustics and bounce as your gauge for levels. Adjust the house and then listen to your monitor for pitch and cues. Loud bands are a big reason why most brides want DJ's at their weddings, these days. Put the ego in check and put out a high quality sound with a classy performance from the heart - and you can work till you can't walk anymore! People love live music if it's performed well. Don't become too automated or dependant on electronics for your sound. Give the crowd a piece of your self, and you'll be a hit.
WHEW! That was a mouthful! Now - go buy some gear, and get to work!
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Uncle Dave