Similar Expenses for Regular Job and Small Business

I have worked for a company for 9 years and receive a W-2. This job involves mostly working in a home office with some travel. The travel involves personal use of my car for local travel and also company paid or reimbursed travel via airlines for out of state. I also own a small business that is a transport company (transporting rescue animals) that drives all over the country. I have large vans, use contract workers to drive, and have normal business expenses associated with a small business, but I do this job (scheduling, marketing, invoicing, etc) from my home office. Can I split office expenses, etc. between the two jobs or should home office expense be applied to only one? Although office space is shared, there are separate office supply expenses for each company. How can I add my personal (non company paid/reimbursed) travel expenses for the W-2 company and also add the small business travel expenses? Both jobs incur fuel, mileage, meals, tolls, etc. I certainly don't want to do the wrong thing, but certainly don't want to miss out on any deductions.