I've not gotten into WvWvW, but would love to learn the mechanics of it. Would totally be down for a set night.
there are quite a few things you can do in wvw to help out the team even alone.
1)follow the zerg, or a zerg. Obviously the point is to take stuff. they do this
2)defend. a place with lots of supplies and siege weapons can be held by a short few hopefully more than long enough for any reinforcements to come and help out. This will net you a shit ton of karma. Even a bronze is 200 some every 2 minutes
3)Run supplies/guard doylaks. A fort with no supplies is wide open. Always repair and build stuff to increase defense. This helps a shit ton and no one does it. Really needs some sort of reward added from anet imo. Like I said, no supplies and your fort will be taken in no time.
4)scout, not for all classes obviously. But scouting supply camps for flipping is helpful. Hopefully you can get some people to help you. Easier with a guild probably. We do this a lot in gaf.
5)create distractions. Hit places and run. Don't flip. Requires a small group. Any less 5 you won't show on the map.
Random stuff
Always carry 10 supplies. Always.(Reminder from Retro below post: Only get supplies from the camps. NEVER the fort) This will carry over from previous maps. Look at the top middle to see how many you have. If you zone in with 0 the very first thing you do is head to a supply camp.
Supplies from the fort should be used while under siege to A)repair the door or wall they are attacking. B)help setup siege. This is why you never take supply from forts unless you need to.
If someone drops a ram at the door, build that shit quick. It'll be focused fire. You have about 15-20 secs depending on defenders til they FF and destroy it. People are idiots and never do this. If a siege is dropped in a smart place build that shit. That's why you got 10 supplies. If you want to be awesome. recall and grab more and come back! Odds are the walls still be up anyways when you get back.
Sometimes the zerg hit shitty targets. Not much you can do about this outside of offering suggestions. Hopefully they cut supplies before going after a big camp. If not, try to get a group and do so. Kill their doylaks whatever you gotta do.
You will die. Probably a lot. But you can make good money too especially if you're defending. Don't be afraid to fight zerg vs zerg. As melee it really pisses me off when I charge in and no one else does. As a guardian I can survive about 15-20secs more than enough time. But people are bunch of pansies and rather turn tail and run. I don't get it.
edit

ne more thing
During a siege if you can't do nothing else. Do whatever you can to STOP reinforcements from getting in. Stun them, root, push back. Guard that entrance. Hang back 20 some yards and kill people before they can get in the door. The Karma comes from killing the lord, not beating on a door.
Never place a ram with oil up.
Arrow carts don't require LOS. Just that you see the target. Place them out of reach as they die fast. These can stop dead zergs.
So there's a short basic primer.