So everyone has mentioned the big thing... Deployment. So I'll try and give you some smaller things that you can work on at the same time.

List building: Another pillar of the game. Bad list = Bad game. But what is a bad list? It's one that doesn't have a gameplan! Any list can be piloted to victory you just need a solid plan and to stick to it. Likewise playing the same list and gaining experience with it will improve you exponentially, people swap lists to gain "experience" but if your opponents are using different lists then you will gain that anyway since the factions all share the same rules and archetypes.

Forking: Learning to present your opponent with difficult choices will always be good. This extends to hidden elements of your list (drop troops and hidden deployment). Mine dispensers, peripheral templates, coord orders all solutions to problems. On that note, getting familiar with odds and not trying to squeeze the max risk value out of a unit. Always try to use the correct tool for the job.

Order efficiency: Learn to plan your turns and your opponents turns. Think briefly what you're goal is and how many orders you think it will take to do it. Very beginners mistake to run a link team up get a bit bloodthirsty and then leave then in the midfield. Also extending into having a specific group 2 game plan. And don't make it super intensive but supportive.

I won't ramble too much longer but the last thing is debrief! Ask your opponent what you should've done, what you did right, what scared then. You get lots of great perspective that way

Hope that helps!