I spent a good hour today cleaning a gun I'd borrowed from a friend of mine. With the help of one of the guys at the gun shop, I gave it a deep cleaning, which I'd never done before.
I love BoreSnakes - they are amazing for field cleaning your weapons at the end of the day. Because I'd used the BoreSnake after I went shooting, the deep cleaning wasn't half as bad as it could have been. The drawback to using a BoreSnake is that you have to have one for each caliber you shoot, but it works so well, I don't mind owning one per caliber.
In addition to cleaning my friend's gun, I tore apart his magazines and cleaned those, too. Here's a big, BIG tip for magazines. Don't over lubricate them and then drop them on the ground, as a lot of IPSC shooters do. The oil attracts the dirt, which gums up the magazine spring and can cause feed problems. And it's just plain gross. One of the mags that I cleaned today had a furry black spring that looked like a coiled up caterpiller (I forgot to take pictures, I was so grossed out).
As long as you don't make a habit of dropping your magazines on the ground (one of my pet peeves, just put the damn thing in a pocket or back in the mag carrier), you shouldn't have to clean you magazines very often, but be sure to do it on a fairly regular basis. The last thing you want is a preventable mis-feed in an emergency.