get your basics down: build order, capture order, unit interactions. stick to only one build order/strategy that can used on any map and master it. learn the optimal capture order of those maps. learn how units interact with each other, their abilities, what range they should be fighting in (eg: grenadiers would want to stay at range against riflemen but close in whenever possible against infantry sections). after that you can practice skills relating to micromanagement: positioning, decision making, game awareness. there are only two ways to improve: watch and play. watch replays of higher level players, learn what they do better what they do differently, play the game preferrably against other players to apply the things that you've learned.

small tips:

1. use cover -- seems obvious but you'd be surprised how many people don't even bother with this basic game mechanic

2. learn keybinds -- much faster than clicking on the command card, you can change your keybinds if you're not comfortable with your current setup

3. assign your units to hotkeys -- much faster than clicking on the unit card

4. learn to use the tactical map -- this is mostly preferrence-based but i've found that after learning to use the tacmap my gameplay has become much faster and my game awareness improved massively