The info given by others corresponds more or less accurately for chip colors in casinos. For home games if your are using only four denominations: e.g.: $1, $5, $10 $25 or quarter, half, dollar and two dollars for my cheap friends, the usual colors are:
least: white
next: red
next: blue
highest: yellow or green or any other color.

You need at a minimum twice as many whites as each of the other two: e.g.: 150 whites; 75 reds; 75 blues and 50 or so yellows.