I flew for almost 8 years. Best job ever. The only reason I stopped is the fact I have 2 little kids at home and didn't want to do 24 hour shifts any more. The hour drive each way wasn't so fun either.
Advice for you? Let's see... first, and foremost, don't walk into anything thats spinning! That's a great way to ruin your day.
When you show up, everyone knows you're there to save their asses, whether it's a transfer or a scene flight. No matter how bad the call is, always stay calm. They see you as someone who can fix the situation, no matter what, so don't ever let them think you can't. Panic on the inside if you have to, but always stay cool on the outside.
One big thing, treat the guys on the ground with respect. Talk to them, listen to their report, let them know they did a good job if they did. I've been in the back of the ambulance when a flight crew showed up, didn't know I was also a flight medic, and was treated like I was the dog shit they stepped in on the way over. Rude, didn't want to hear anything I had to say, took my written notes for them and tossed them in the trash. Don't treat people like that.
Don't expect every call to be blood and guts and excitement. There was a lot that were simply transfers that took 30 min by air vs 2+ hours by ground.
Know your drugs, your RSI doses and vent settings. I carried a couple little cheat cards with me, do what you need to do for those. Know your equipment in and out, how to troubleshoot it and what to do if it fails on you. At the bedside or in a field is not the time to try to learn how to use something. Know where your equipment is, especially the obscure things you don't use often. Again, when you're with a patient isn't the time to have to go searching through the bags to get something.
One thing I started doing very early on, and still do to this day, is when I had to intubate someone, I use a bougie. Doesn't matter if they have a perfect airway with vocal cords lit up like a neon sign, I always put a bougie in. If for some reason the tube wouldn't pass and you need a smaller tube, or if they started to vomit and you needed to suction, your path to the airway was there and secure. Lay the bougie to the side and you can bag them until it's time to try again.
I always carried a few extra company pens and carabiners with me, toss them to the guys on the ground, they love that stuff.
Keep your eyes outside if you don't have a patient on board. Keep your phone in your pocket, Facebook can wait till you get back to the base. This is especially important when you're landing at night in a remote place. Look for wires, stuff on the ground around the LZ that can get blown up into your blades, bystanders or firefighters who want to stand in the middle of the LZ, basically anything that can make an uneventful landing an eventful one.
Most of all, be safe and have fun. You're getting to do a job that a lot of people would kill to do, but never get the chance.