When you file your LLC with the NE Secretary of State, or file for a tradename with the Nebraska Secretary of State, they will ensure no similiar names would be filed that would have a likely impact of consumer brand confusion.  As a result, if you are only doing business in one state, I don't think I would worry about a USPTO trademark initially and just concentrate on making money first.  On the other hand, if you have a great name for a business (and not just using your last name), and you are doing business in all 50 states over the Internet, investing in a trademark might be worth the money.