1) Keep ALL receipts! No matter what do NOT throw them away. Scan them into a document if you have to. For any food receipts I recommend to write down who you met with and why you met them or ate there.
2) Do not use personal checks or credit cards for business expenses. If you have to use a personal check or credit card fill out an expense form and pay yourself back.
3) Keep track of your mileage for all business trips. Include date, where, start and end mileage. Purchase a small calendar and before leaving the house/office grab it.
By following these three tips your expenses will be in the correct category, mileage will be more accurate and possibly more mileage recorded for tax time, and personal finances will not be mixed in with business.
What do you think? Do you keep your receipts, mark them with notes, mix personal with business, and track your mileage?