Hi ML
The biggest tip I can give you when becoming an affiliate marketer is 'stick with it'. Sounds easy but most internet marketers, me included, seem to suffer from ADD

and jump from one process to another. Find one process that works and stick with it until you know it's working, if after a month or so it is still not working abandon it and go on to another process.
It took me a year to learn this and when I stuck with one process that's when the money started coming in.
To get you started the best and least expensive ebook I can recommend is Dennis Beckers '5 Bucks a day'. He explains that you should aim to earn $5 per day with affiliate marketing and work yourself up from there. He is now earning around $5000-$10,000 per month with this simple method.
The link to his site is
5 Bucks a DayI have to say I am affiliated with Dennis Becker as I am a member of his paid forum however I would never recommend something which I did not believe in and it was Dennis's site which saw me going from $0 per month to $1500 per month with affiliate marketing.
Hope this helps
Steve