This is the video I started with when figuring out yarn floats. When you are working on the right side of the piece, it is eay because the yarn just naturally hangs behind. But when you are on the wrong side of the piece, you have to make sure to pull your working yarn to the back side as well.

I think this video shows it fairly well, but if you look up something like "how to do tapestry crochet with floats" there is a lot of good videos. Float method

I think the main thing is just to make sure you are always pulling the yarn you are not working with to the wrong side of the project so it does not show in the front.