As a fellow noob to IDPA, I shot my first match a week ago, I can tell you one thing: slow down! It took me about 3 stages to really slow down my mind and just do one thing at a time. Now that I've done it once, I'll be much faster next time.
I learned a ton and had to adjust some things I had been already been taught. The first thing I had to alter was my speed reloads. I was taught to reload a semi auto with the gun up close to my sight line, muzzle oriented almost straight up in the air. This was a no-no on the range we shot on because of the backstop.
Second thing I learned and changed was my movement from point to point. I was often too slow moving between cover. I started running on the later stages and it did shave some seconds off my times.
The final big thing I learned was how to use cover in a way that satisfied the rules of the game. I kept putting my foot or leg too far out and it cost me some penalties. I got better as the match progressed, but early on I did it wrong a lot.
It was a very fun and very educational day for me. I cut my fingers up a few times and on the last stage, I bled so much, when I did my first reload the mag actually slipped in my hand. I looked down at the mag and realized I was bleeding all over it, my mind took over, I fix the reload go the gun running and wrapped up the stage without an issue. It was one of those moments where I realized how much a good grip and aggressive texturing could matter in a situation where I might need to use my gun in real life.