In addition to what the other guys have said, you're going to need to clean or replace the spark plugs.
If this bike has an in-line fuel filter, you need to replace that.
Wipe the rust off the brake disks.
Lube the chain. Repeat: lube the chain.
If the fork tubes are rusty, you need to wipe off the rust so it won't destroy your fork seals. If your fork seals are already leaky, you need to replace the fork seals, change the fork oil, and pressurize the forks (this is a big enough hassle that you should just have a shop do it).
You need to inflate the tires.
Wipe the dust off the exhaust pipes and engine (or it'll scorch when you start 'er up).