Can anyone give me some help and info about affiliate marketing?

Ok, I want to be able to earn a bit of extra cash in my spare time and I’ve heard a load of hype about affiliate marketing. I’ve never tried to do anything like this before but am thinking of giving it a go. I’ve been looking at stuff on the internet to do with this and it all sounds great but is there anyone here who actually does this and makes money? Can anyone give me any hint & tips to get started?

Any info would be greatly appreciated!!!