Haven't shot IPSC but I'm fresh off my first action shoot (carbine event). My #1 goal was just to keep things 100% safe. Finished at the bottom of the pile, with my score WELL below my actual shooting ability, without warnings/infractions, learned a lot from my mistakes and had a big grin regardless of the score. That's about what I expected and am not disappointed one bit. Remember that shooters in general are a friendly community and will go out of their way to ease you into the fold. Just be safe, take your time, you
will have fun and you'll be fine. Here are some of the lessons that I picked up (carbine event)..
1) Make sure your equipment is dialed in right when you take it to the tournament and double-check it in the safety area. [remember no handling of ammo, snapcaps or brass] - I lost a lot of easy points because my gas reg was set on 0, meaning I was shooting 3s doubletaps on bolt-action
2) Inspect your targets - Lost a lot more because I didn't pay attention to my targets and was grouping way too far to the left; could have corrected my point of aim and saved more points
3) Dedicate time to "unusual" shooting situations like one hand, weak hand, positions and transitions; dryfiring will help you a lot - Lost some more because I had noone to show me barricade shooting (can't practice with the action crowd without a holster cert and I'm about to go for my BB)
4) Make sure you're aiming at the A before you squeeze that trigger - I was tempted to fire before I had my target properly in sight during the #3 fiasco, didn't do it but the temptation was there - first time out, all awkward, you really wanna make yourself not look bad, but remember that safety's always #1 in all shooting sports except for MLI
5) Watch your 90's and your trigger finger. That's a lot more important than engaging your targets
You'll give the best impression by just making sure you go through the tournament safely. Good scores come from practice and experience (making mistakes and learning from them).