Sanding a guitar top, what type of sand paper should I use?

I need to re-finish my vintage acoustic. The paint is old cheap paint that chips easily. I got most of the fretboard done with a nail filer (hey! I am a girl). Which worked very well, might I add. Now I need to sand the top, which has a very THICK glossy finish. I need more than a nail filer for the job. I'm worried I might scratch it. It def needs a redoing. I have seen old guitars being refurbished (worked at an old guitar shop), so I believe I am prepared for the task, not that I am expecting it to turn out perfect. I am thinking gentle, what type of sand paper would you suggest I use? Thanks for the help!