If you are self employed you're record keeping requires a bit more finesse. You need proof of every deduction you claim. NO RECEIPT = NO DEDUCTION. I always advise my clients to total up all of their receipts for business into separate categories such as supplies, advertising, repairs, etc. Then bring in the totals. This saves a ton of time for everyone and I guarantee will make your preparer very happy.
Email firstname.lastname@example.org for a complete list and with examples of a company profit and loss should look like.