I’ve been asked to shoot a variety of subjects while working for the campus magazine. Anything from organization meetings to a Kid Cudi concert and I’ve had different times to prepare. Sometimes a few days and sometimes a couple hours notice, such as the case with Kid Cudi (I had to step on some toes at work that day) but irregardless it’s important to have the appropriate gear for where you’ll be shooting.
Most importantly, make sure your battery is charged. My Nikon D90s battery takes a couple hours to fully charge, so I tend to charge it the night before. Nothing is more frustrating than watching that little bar tick away, until it’s dead and you miss your shot. Not only do you miss your shot, it’s very unprofessional. Even if you don’t have a fancy battery grip like myself, keep a few spares in your pack.
What pack am I using? Up until now I had been using a small Tamrac bag, but since I’ve acquired a battery grip and a few other accessories I’ve been hauling my stuff around in a Lowepro Rover AWII. It’s a good camera backpack, but for dedicated gear hauling you’d be better off with something like a Lowepro Pro Runner 300. It has more space to put your gear for shoots. The Rover is great for hiking, since it has a top section where you can put your coat or beef jerky but for photo shoots it’s rather limited.
Nikon 55-200mm, great if you're on a budget
Make sure you have the right lenses for the situation. Since I’m a poor college student, I don’t have access to all the f/2.8 glass out there, so I have to make do with what I’ve got. Most of the time, I use my 18-105mm that came with my D90. It’s a good lens if you can get over the low light handling, and it covers a wide focal range. Making it an ideal lens for shooting group meetings, or anywhere in a somewhat cramped environment. I also pack my 55-200mm for when I need that extra bit of reach. This lens does poorly in low light, but it gets the job done and is rather cheap, $169 on Amazon. One lens I’ve rarely used is my 50mm f/1.8, surprisingly. While it’s wide aperture would be great for low light situations, I find the lack of zoom to be annoying.
Sure that nice, wide 1.8 aperture would have been fantastic when shooting Kid Cudi, but I only have one camera body and changing lenses in the field is something I like to avoid.
Next, a hot shoe flash. I’ve taken one on assignment, but that’s because I did not own one at the time. Trust me there were plenty of times where a flash would have been a godsend, but you can get by without one. If you’re packing a flash make sure you have spare batteries for it too. I’m using a Nikon SB-600 and four lithium batteries. I haven’t had to replace them yet but that’s not to say they won’t die soon.
Also, make sure you have plenty of memory cards. It really stinks when your shooting a once in a lifetime deal and you run out of memory. I carry three 4G Sandisk Ultra memory cards and they haven’t let me down yet. They’re quick, reliable and they’re 
reasonably cheap compared to the Sandisk Extreme cards.
If you really want to haul your laptop into the field to download photos more power to you. I don’t just because I do not like the added weight, but having a workstation is rather nice.
Finally, if you have time organize your gear beforehand. It’ll make life a lot easier when it’s game time. There have been plenty of times where I put off setting my gear up and paid for it.
So don’t procrastinate.
Most importantly, what gear you take with you is all up to you and where you’ll be shooting.
