Oh you're may be sorry I replied to this - I come from a business background, having done quite a lot of stuff like this and can get really carried away!
A mission statement should be 5 things - SMART! S = Specific, M = Measurable, A = Acheivable, R = Realistic and T is Time-able (strange word, I know, but it works in this case!
So, example, a statement like
"I wanna be the best"
sounds OK, but is not any of the above, ie there is nothing specific stated you want to be the best at, there is no measure of whats is the best, so you don't know if you can acheive it, it is impossible to tell if it is realistic and there is no time against it again, in so much as measuring it!
However, this building these factors in, a mission statement would start life like this.
"We wish to supply the best quality nail treatments to all our customers, at a price they can afford, always"
It has all the SMART factors, and means something that everyone can understand.
Now, I'm not saying that this one is exciting...you probably have some great ideas of what you can build around you business, but a mission statement should be a simple statement, that you can then build a much stronger marketing statement around.
OK, so, sorry its long, and probably pretty boring, but it should help you start thinking about it in the right way and then you will come up with some great ideas yourself, which I'm sure there will be loads of geeks ready to pass opinion on!!
Hope this is useful
Lyndsay x