You can trademark your logo. Actually, it's the service mark. sm, which you will be using because this is a service, trademarks are used for products.
here is the link http://www.uspto.gov/
I have got Lawn Guy letterhead, Lawn Guy invioces and Lawn Guy flyers.
Once you get your logo digitized into a "OMF" or "DST" file you can have it embroidered onto a cap or shirt. The place I went to, "Embroiderme" charges
$2.50 for a 2 color baseball cap and $7 for the embroderie so for under $10 you have a nice professional hat. You can get green khaki pants at a used uniform place for $5 and a nice beige long sleeve button down shirt for $3.50
at goodwill. Bingo, you're professional uniform for $18. Summertime you can get these underall type sweat-through athletic shirts and have them embrodered with you logo for the heat.
The only expensive part is the digitizing of the logo file from .bmp .jpeg or .pdf to OMF or DST. The embroderie place charges $80 for that.