I’m working on getting my extra class license. Here are a few things I have found that help. Even with a background in electronics and years of being a ham I still score about a 50% on any practice test I take.
Here are several places to get study guides and take sample tests. I use my phone to take practice test ofter.
Check out Dave Casler, (KE0OG) youtube videos. These are very nice and a great resource.