You could very easily spend more money fixing up the bike than you could sell it for. If your looking to make a few bucks, sell it exactly the way it is. A prospective buyer is going to want to put his choice of tires and tubes on it anyway and tune up the bike even if someone else said it had already been done. If your looking to ride and enjoy it and you don't plan on purchasing the required special tools to do your own work you should take it to a bike mechanic as this would be less expensive.