To promote a professional image and set yourself apart from your competition, you must use a professional looking invoice. Customers appreciate having a paid invoice and you will find that all commercial work will require it. The invoice that I use carries my logo, name and address, and has a place for the customer to sign that they have accepted the job as completed. I leave a copy with the customer and keep the signed top copy for my files.
You can find handyman invoice templates here. Print out the template; paste your logo at the top left and your name and address into the top right box and take it to your local full service copy store. Have them create 2 part NCR (no carbon required) forms. You should end up with 200 invoices for around $50. This is a real bargain when you consider the level of professionalism you just added. If you will be doing commercial work, you should consider having the invoices printed with sequential numbering. The numbering can be done at the time the NCR forms are printed. Aluminum invoice boxes can be purchased at office supply stores to hold your invoices.