Here's some basic advice that's helped me over the years.
• It's called fishing not casting. As you become more comfortable limit false casting.
• Learn how to tie knots and double check them. Big fish break bad knots.
• Don't stress about matching the hatch. You can fish with a streamer during a mayfly hatch.
• You don't need specialty “fly fishing” gear. Spend money on going fishing, not buying gear.
• Pick one fly and learn to fish it. It's kind of like having a go-to swing, club or whatever that gives you confidence.
You're in a great place to start fishing. Have fun with it!