Get a couple of decent cloths. Isopropyl alcohol for cleaning stubborn stuff and clean the barrel once every 3 months. This is a very well documented question though and is a good example of why you should use the search before asking as it's asked every month or so. You'll get much quicker and better answers if you look by yourself first, then fill in the gaps later through asking.
http://www.airsoft-forums.co.uk/index.php/topic/28054-cleaning-with-isopropyl-alcohol-vs-silicone/ covers everything in depth. As above though:
Clean with isopropyl alcohol (kitchen towel is just as good as buying the pre-packaged alcohol wipes, but a lot cheaper)
Use a cleaning rod
Try not to get too close to the bucking (though you may want to do one run over it just to remove any lube that's made its way down your barrel from the gearbox (AEG) or gas in the magazine (GBB)
Finish up with a swab of silicone to keep the barrel slick and to make BB fragments not stick as easily to the inside of the barrel
Do not get lube on your bucking - best practice is to make markings on your cleaning rod so that you know exactly where to stop
I guess to answer your question: 1lt of isopropyl alcohol (around £6-8 on eBay) or a pack of alcohol cleaning wipes, some kitchen towel, cleaning/unjamming rod for barrels. For everything else a couple of rags and a couple of lint-free cloths too. Lube wise I use silicone or Frog Lube - some recommend just silicone, some recommend nothing and some recommend other branded stuff. There's no particular consensus on this but don't buy something with loads of additives as it'll rot the seals in your gun (less of an issue with AEGs, but more of an issue with GBBs).