"How do I get good at drafting" is such a big topic that multiple people have made years-long podcast shows about just that. One thing you can do as a new drafter is to "study" a set to gain familiarity with it before you get into a real draft.
You can practice evaluating and picking cards on a site like Draftsim.com. For past sets, you also get the benefit of community-wide hindsight, with loads of articles, social posts, and podcast episodes to study. You're aiming to get to the point where you think beyond just open colors and start building your deck during the draft itself.
As an example of deckbuilding during the draft, it's not just recognizing that black is open, but that there's an important black card here for the BG [archetype] deck. What other pieces of the BG deck are you hoping to see to convince you to commit to it (as opposed to another Bx deck)? Which cards, even if they're pretty good, are replaceable enough that you're willing to pass them to mine for the more key cards?