First site

What interests you and what are you passionate about? What do you have some knowledge about so you're not spending a ton of time researching to obtain knowledge about your chosen niche.

Start there and see if there are people buying information or products related to your interest. If not, what else do you have some knowledge about or are you interested in?

First, I must say I like your attitude. :-) When it comes to choosing a niche, it should be something that's both profitable and something you have interest in because you are going to have to stick with it to see results. It also helps it you already have some knowledge about it, too. Don't look at competition as a bad thing. It just means there are lots of opportunities for money to be made. All you have to do is get your foot in the door. Also, Amazon pays really low commissions, so if you go that route, you are going to need to sell high ticket items and get lots of traffic.

Once you decide on a niche (weight loss - one of the big 3 along with dating and make money - I know Squidoo isn't fond of either of those but lots of sites to choose from), it's important that you get the right training and lay the proper foundation. If you haven't already done so, I recommend Unstoppable Affiliate by Andrew Hansen and Josh Stanton. It uses a realistic approach to teach the newbie marketer how to take advantage of all that a niche blog (the name for what you want to create). Outside of the basic course, they also offer a coaching program you can take part in.

Good luck,
Joey