Look for hoop size! Most people start out with a machine only to realize that they would have loved a larger hoop...get the machine with the largest hoop that's in your budget.
Go with a known brand...always safety in other people's experience and a good brand.
Look at the size of the screen..it is no fun at all to look at a design on an itty biity screen.
Don't forget to watch for sales..September is national sewing month..there will be deals .