I carry a small container of 2-stroke oil and a squeezy ketchup-container with an oil-level mark. When I fill up, I start with putting oil in the squeezy, and then shoot a few ounces of gasoline...swirl it around, dump it in the tank, then blast away from the pump into the tank. This works especially well in the Winter then the oil gets thick. I'd had problems in the past with unmixed oil globs getting not the carb. Like Slogger sez: you should clear out your carb (it's a good opportunity to familiarize yourself with it, as you should anyway), and check that your plug ain't oil-clogged. Although it's probably not the case, I WOULD verify that you still have a spark if you're having trouble starting after this foul-up.