Mostly it's practice! some people swear by a 1/4" foot, some have a little piece you bump the fabric up against. Others use a stack of post-its to guide them. but mostly it just takes practice. Other hints i've heard:

don't watch the needle, watch the fabric as you guide it to the needle.

find a speed your comfortable with and put a block or book under the edge of your foot control so you can't speed.
Above all, don't get discouraged. many of us on here have been sewing for years and we still struggle with some things. we're all still learning.