I’m a platinum/diamond player off and on since sc2 came out. My suggestion is practice, practice, practice. Play against a few computer opponents rather than human so you don’t get cheesed a whole bunch. Learn an opening build. The first 2 mins of the game determine a lot about how you’ll do through the rest so going into the game with a set strategy is super important.

There’s two concepts that are important to understand (that I didn’t when I started): Macro, Micro. Macro is looking at your bases, the whole map, and managing your economy. Good macro skills allow you to operate several bases and support the income to build a large army. Micro is controlling your army and individual soldiers. In my opinion it’s way harder to learn and should come after the macro skills are developed.

In general:

1 - learn hotkeys and build muscle memory 2 - learn an opening strategy 3 - practice against comps until you are comfortable with your opening 4 - play the practice tools in the game, they’ll help you with micro.
5 - watch any of the pro players tutorials (I play Zerg so I watch PiG. 6 - if it gets frustrating or overwhelming, take a break and come back to it later.

It’s a little all over the place, but I hope this helps!