Focus on the Fundamentals.
Choose an application of software that is the most suitable for you or your "forte". In my case, I started with Photoshop and now I'm trying to use other software.
Find your own Design style. there are many design styles, you can search it up.
Look for references. There is no shame in looking for a reference when designing, I would suggest pinterest BUT DON'T EVER STEAL SOMEONE'S DESIGN.
Last but not the least, Practice makes perfect. Specially if you're not a very creative person like me, you need dedication and keep on practicing.
Good luck!