Off the top of my head the best increase I know is called a lifted increase. Before you knit the next stitch you knit into the stitch on the row below it. One of these here or there is not going to show. If you have to keep increasing row after row, though, like if you're knitting a sweater from the top, you will want to plan it out in advance to make a nice little ridge, or something. I googled "lifted increase" and it looked like there were some good clues on the first page of results.