I’m probably in the same boat as you. Have a few projects under my belt but my work never looks as good as the pros. But remember that pros do this all the time, this is like your first or second time doing some of these things. Give yourself a little bit of a break. I saw this video a while back (sorry it’s Facebook, only place the post it) and I realized I was not using my tape measured correctly: https://m.facebook.com/ThisOldHouse/videos/897033664132898

You could also be having issues when you cut your materials to length, are you not getting the saw blade in the correct spot so the item being cut turns out slightly too short or long?

You may want to get some longer levels. I have a 3 foot and a 5 foot for larger projects, helps me when I’m trying to level bigger items. Also, what sort of levels do you have? When I got my first house my mother bought me some basic tools from the bargain bin at Menards. The first level was all plastic and itself was not all that straight. Insert little blip here about how it may be worth a couple bucks more for some of these more essential tools.

When you are mounting shelves are they the ones with the brackets? I usually drill the first hole, then secure the shelf via the first screw to then level the shelf and drill the second hole through the bracket. I don’t trust myself to drill 2 holes without measuring between the first and second.

Remember seeing a post like this a while back and some dude who makes glass containers commented that this is a manufacturing defect, something about uneven cooling I believe. Too lazy to go find the other post, but I assume someone will dig it up after reading this post.

Now do the rest of the characters!

Found this a while back when I was working on a Cub Scout adventure. Probably one of the most useful $6 I’ve ever spent!