This is the First Step I highlighted in the Intro Post, "Keywords and Competitive Research", to this Series.
ONE: First you need a tool (or method) that is going to help you pin down keywords people are searching for and products that are in demand. You need to feel rather confident that someone is actually buying a product (or service or..). These type of tools, sites (or services) will help you identify products that look good to target.
These keywords stem from or are related to specific product names and descriptions. This is the perfect place to start as these are going to stand the best chance of converting into affiliate commissions.

This process will lead us to a place where you'll have a Niche Worthy to attack and build a niche site around.. one that stands the best chance of succeeding in the short to long term.
Some people might think to first start with choosing a market, building a website in that market and then going out to see the products they can put on the site (not always based on much reasoning.. they just look nice and they have a good looking sales page). So they are doing the product research towards the end of this process... if at all.
But from my experience it's much more effective to first hunt down a great product that people are buying in droves and is already successful... and then identifying that market, the keywords and building a website around this to drive traffic to. (What we've always done with the Blast Method... in the PPC Arena)
How do we do that?
First, you can start by going to websites that provide you important insight and data you can use to come to the right profit conclusions and the decision to do more research on a niche.
One such place is to find sites like Yahoo's Buzz. Here you can use the search function available to you at the top and start plugging keywords in that might bring up buzzing products. For instance you might start with 'toys' or 'gadgets'.
When you uncover something in Yahoo Buzz that looks interesting, do some more searches on Google.. go to eBay and see how popular it is there (use the eBay service I mention below).
You can also go into your other Affiliate Networks and see what merchant's are offering these products. You may be able to determine how well it's doing in the network or on those merchant's sites (best seller lists etc).
Or you can go right to your Affiliate Networks and explore merchants there. Again, see what's hot using the network stats or go to the merchants sites to see what they are displaying.
eBay provides an incredible opportunity to see what's selling online and what's popular.
You can use eBay's own 'eBay Pulse' to search for popular items that are successful. Or there are many other tools and services developed for eBay, using their API, to collect and display that data better.
One such source is: eBay Watch Count
Here's an interview Jake Becker at WatchCount.com
Browsing their help section alone can give you more insight into the power of this data!
Their model is actually to make money from consumers searching and buying items after they've clicked through on their site to eBay, but sellers (and affiliates) can use it to see what's trending and popular.
Any other source you can find that helps you pin down Hot Trends, Hot Products and Best Sellers (where you can be reasonabily sure people are buying these products), is a good place to start. There's just no sense in building sites around products that don't show any promise or you can't determine in some way people are actually buying!
There are many other sites out there that provide 'Best Seller' lists. Open a dialogue with a merchant. You could contact merchant's and ask them what's hot; they could tell you what sells best on their site or what other affiliates are having success with (or the methods they are using.. don't stop there ;).
Keep your eyes and ears peeled in general. Even offline you can uncover profit opportunities in magazines, in your mailbox or via conversations with friends and family. What are people clamoring about?
Some of you may just be interested in finding great digital niches (e.g., info products, software). Maybe you are more interested in building Name Captures and follow up systems.
Then you'll need to use some other tools to help you pinpoint hot trends and markets.
There are sites like CBEngine that can give you insight into what's doing well on Clickbank.
I'd recommend hanging out in forums (communities) or niche social circles dedicated to certain types of markets and see what people are talking about.. what's the buzz? Who's reviewing what?
Find yourself on e-mail lists in various markets and see what other marketers are talking about or promoting.
GATHERING...
During this process, create a spreadsheet and jot down or collect those opportunities. I'd recommend to try and hit a variety of categories and create a list you can take into the next step.. Pinning those keywords down!
As you are starting to see there are so many incredible resources developed to help you as a niche marketer. Direct your efforts towards those things that stand the best chance of succeeding and making you money. Use them!
-Matt Levenhagen
Niche Marketing - Niche Research