Fazc has covered your attempts, so in regards to your warm-ups, it's always good heading into the meet with an idea of what you'll be doing so you don't waste time in the warm-up room thinking about it. So if your opener is 155 then do something like 20, 60, 100, 120, 140, perhaps. You'll be warming up with your flight, and possibly another if there are two platforms, in a separate room to where the lifting is held. Or at least a cornered off area with a multitude of racks and weights. I've always found everyone to be friendly and helpful and up for some banter and spotting so you'll find it a good atmosphere.
You write your openers down on an entry form thing you'll be given at the start of the meet, along with weight, rack height, etc. You can change these up to approximately five mins before your flight starts, give or take. Again, judges and referees (well, most of them...) are friendly and helpful.
If there's anything else, feel free to ask mate.