Sound Presence

Recently, I listened to a very good local band. They were together, harmonized vocals, had clear dynamics, and the system was powerful enough to reach any vocal level you could possibly need...but they sounded unprofessional.
Why was that?
Even though the speakers could handle the volume, they weren't controlling the sound properly that they were sending to those speakers. It's a tight balance between having no processing (raw) and too much and sound cheesy, especially in small and medium sized venues. If you put an echo on a system in a small room it may be hard to take yourself seriously, but leaving that sound raw could be even more unforgiving.
Bands with a dedicated sound person will change effects and processing throughout a show, but what sound you want will be different from other people depending on your style of music and your concept for a song. Try going to a music store and trying out all the various effects, choruses, echos, and what-not. the bigger the store you go to the more that they will have in house to try, and on average, the more knowledgeable their staff will be.
Don't let that last step of the process comprimise your sound.

Does Your Band Have A Rider?

Expanding from a garage band toward a profitable concert performing success story requires a lot of transitions. Are you prepared to handle your next venue? Is the venue ready for you? Having a band rider is an effective way to get all of your ducks in a row well in advance.
A rider is simply a paper that lists everything you expect/want/need from the organizers of an event. Make sure anything that you absolutely need is listed. You can be as specific or vague as you want, and be flexible too.
The idea isn't to scare off anyone that might want your band to play, but conversely to show your professionalism. How many power outlets does your band need access to? If you are using their sound system, how many inputs will you need? The clearer you are on your needs, the more likely your show will be a success. Try going to successful bands websites that you like, they probably have a section somewhere for booking, and take a look at their rider. The more demand for the musician, the more specific they get. As a place looking to host live music, they will usually apreciate the lack of "winging it" when all eyes are on you...but until you really hit it big, don't ask for the moon.