It all depends on what you are fastening together. Fasten a 1/2 plywood to a 1x3? then use a wood screw 1 inch long. Fasten a 2x4 to a timber? 2 1/2 would be about right. When you say star head do you mean philips or the specialty multi point shapes. 10 gauge are heavier than I used. you can get a lot of screws for not that much money. Best to use what is right for the material being screwed.