Honestly, the best way to get better once you have the basics of modeling down, is to just design stuff. You can do tutorials and draw up stuff from books, but the only way to get experience using CAD like you would as a mechanical engineer working in the real world is to design stuff and go through the process yourself.
There are a lot of really smart and helpful mechanical people here on chief delphi who love to see designs people post, and can provide specific feedback.
Both SolidWorks and Inventor are great pieces of software to learn with. SolidWorks is a bit more widely used, and in my opinion, a little better, but Inventor is still good.
A few things I notice students tend to skip when learning CAD are organization and drawings.
Often times, I’ll see a student give a part a name like “wheel”, “new wheel”, “fixed wheel”, “better wheel”, “super awesome wheel of death”, “Part1”, or something equally unhelpful. I find it’s really nice to set up a way to deal with parts. A student on my team came up with a helpful numbering system for parts that he drew to be manufactured, parts that he drew to be purchased, and parts he downloaded from the internet to be purchased. Just having a consistent and neat way of organizing files makes it so much better when looking through a few thousand parts to find the right version of what you’re looking for.
Also, students seem to never learn the right way to make an engineering drawing for a part. SolidWorks and Inventor both have really powerful tools for making drawings, and complete and detailed drawing are very helpful. They’re much better to send to machining sponsors (as they usually have issues importing whatever 3D model you’ve sent them, even if you send it in almost every format), and it’s nice to have a binder full of drawings so you can make a replacement part quickly and correctly at competition, or at home, if the original designer/manufacturer isn’t there. To learn this, I’d recommend looking at some tutorials, then just trying it on your own. If you’re really interested, you can look at some GD&T books/websites, which have detailed descriptions for what every dimensioning symbol means.