In my opinion I think the best thing to do is to try and picture as much of the build as you can in your head, don't build blind without knowing how you want it to turn out. Plan it out on a piece of paper if you have to, but even doing that you will end up making changes. Also when building stick with the same blocks, type of detailing and use of depth throughout. Other than that just don't give up on what you've started building, I've done that way too much in the past and scraped projects because I didn't like how they were turning out, so if you don't like what it looks like, don't start from scratch just change what you don't like until you do and just practice.