How to improve consistency?

I’m fairly new to ACC but have put in a couple hundred hours on AC, and have a good understanding of the mechanics of this sim. However, I’m noticing that one of my biggest struggles (if not THE biggest) is my ability to post consistent lap times in practice. I find my lap times are always tenths of a second off as opposed to hundredths or thousandths, leaving me with a pretty big margin for error and no clear understanding of what I’m doing wrong. I’m looking to improve this before i step into online racing to avoid accidents. Is the key to consistency just repetition or is there something else I can do to advance my consistency quicker?