I found TrueBlox a few years ago after seeing their posts on Instagram and was really being blown away by their quality of bodywork and paint. The tips section of their website has a TON of really good info. I bought a set of their wetsanding blocks before they started selling full size blocks and noticed a difference in how well they flattened the texture out of clear. Since we do a lot of glass work we have plexiglass drops so I made a few blocks to try on bodywork. They cut faster and flatter than foam blocks and find all of the high and low spots quickly. It takes a bit to get the hang of choosing the right block for the surface you're working on but once you get the hang of them they're a huge help in getting flat areas straight and curved areas shaped correctly. If I didn't have plexiglass drops already to make blocks from I'd definitely buy a set of their blocks.
https://www.trueblox.com/pages/true-tips