Before Starting you need to Know a few things:
If you have done your research you should know there is money to me made in Affiliate Marketing. Before starting make sure to consider the following:

* Know what your goals are and set them reasonable.
* Find out your budget.
* Figure how much time you can spend each day applying what you have learned.
These steps are very serious.
You must have a goal to set out for within an allotted amount of time or else you will have wasted your time. Like the old saying goes "time is money".
You need to be very organized with your finance portfolio and very disciplined managing your monthly budget.
You must be ready to devote yourself on a daily basis, building new skills and learning as you go. Any good affiliate knows 80% of success is in the Research.
If you follow these steps and stay committed, you are setting yourself up for success!

You can spend countless hours researching an endless supply of online programs. Here are a few things you might want to consider: 
* What is the quality of the educational materials? * How much are they asking you to spend & are the fees one time?
* What type of guarantee do they offer? 
* Do they offer a 100% money back guarantee?
* What are other customers saying about them?
* Do proper research, go to blogs & forums read about the product or materials you are interested in purchasing.
* How old is the program?
* This is very important. The Internet is steadily changing. Make sure it is fairly new or if the product has been around for a while check to see if they offer updates. If not stay away!

My Personal Thoughts:
Honestly, you will make mistakes and everyone does in the beginning. But you don't have to waste money. This I have done a little bit of on the road to success. Wasted countless hours and enough money to pay the bills for a couple months bills. This taught me if you can't handle failure you are not ready for success inAffiliate Marketing. I still advise doing a lot of research on your own to keep a sound mind.

* In the beginning I joined a program that had a one time fee of $35. This isn't much money and they offered me a great sales pitch. Huge mistake. The program I had purchased was over "4 years old". They didn't even have one update since it was released & the free promotion they offered to reel me in could be found with a little research online. Actually, I found sources to all of the information they provided for Free and it only cost me a couple hours (not $35). 
* A couple weeks later I started doing researching again.
Do you know how many "free" programs" are offered online. There is always a catch though. Luckily by now I had enough knowledge and know how not to be sucked in by every program that caught my eye.* I was fed up. No matter my limited skills I knew that I could succeed on my own. Another Mistake. In the end I was trying to market products I had not properly researched. The payouts were poor and their commission structure had no foundation. Obviously I ended up spending, well lets say wasting my money on advertising.

I eventually found a affiliate training community site for aspiring affiliate marketers, called Wealthy Affiliate University. I will personally vouch for this program. Once you join you are part of an online affiliate family. The educational teaching materials are excellent, up to date, and will blow your mind when it comes to IM "Internet Marketing". 
If you like options look into "Affilorama". I am a member of both these programs and the information they provide is like nothing else you will find online. Don't waste your time and money. Choose and join the "Wealthy Affiliate" family as the top affiliate program for all of your Internet marketing needs.