Actually they say it is best to only do one coat on your fingernails, they say this helps prevent it. You want to do two on your toes though, and you want to make sure you put on a good top coat to prevent chips and give it a nice shine. Like Artiiparti said if your nail polish is low quality there is a better chance that it will chip quicker, so it may be worth it to invest in nicer nail polish.
Two coats of polish and one top coat.you should also invest in long wear nail polish.they claim to last 10 days.they don't last that long for me because I cook and clean and have two kids.but you can extend their beauty if you use gloves when you clean.
Put a clear coat over whatever color you wear, this should help it last longer. Take it easy on your nails too. The clear polish helps them shine better and last longer. I use two coats of color and one coat of clear. Hope this helps.