I see a lot of 'gurus' advising the new IM'er to choose a niche which is low in competition. Im going to go out on a limb and tell you to do the opposite. You should be drawn to competition like flies to a turd. Competition means one thing; there is money to be made in that market. Search for the keywords of the niche you want to go into on Google Keyword Tool, and you should be looking for a niche which has a GMS (Global monthly searches) of over 100k. That's your niche. There is plenty of business to go around. Too many people fall into the trap of trying to zero in on a narrow market and cater to that markets specific needs. While I do believe in catering to the specific needs of your market, you can let the $$$ come to you if you choose to go with a more in-demand niche. Aslong as your product is good quality, your copyrighting is effective and your traffic is strong, it doesn't matter how many fellow IM'ers are in the market.
Kevin