My first day wasn't the best, and in retrospect, on a pretty bad field (the "neutral area" was literally almost in the middle of the field- I'm not kidding- and there were no chronographs. I could also add that there were no barrel plugs, but back then, they were new and really only a few fields down in the states had even heard of them.)
I'm pretty sure I got no "kills"- as it was called at the time- and went through at least two full boxes of California Magnum (200 rounds per box) that cost something like $20 each. Maybe $25, I can't recall for sure.
Today, most fields- organized ones- are generally run much better, but there's still more than a few Karl's Kombat Kingdoms out there...
Actually, the worst thing I keep hearing about is TWIBs- tourney wanna-bes. The field puts the "regulars" all on one side ("Hey ref, we all want to play together!") and puts most or all the newbies and first-timers on the other side. So one side has a bunch of kids who don't even know where the flag stations are yet, who are trying to make their 200-round allotment last as many games as they can, against the kids with the $1000 guns, who brought three cases of paint each, and who are trying to "practice for a tournament".
Some fields keep 'em in line, some don't.
Anyway, just remember your goggles and your barrel plug, and to enjoy yourself. It's all in good fun.