Authority Sites Are King : If you plan on getting most of your traffic from search engines then I highly recommend making an authority site. New items added to your existing site get ranked more quickly than new items added to a new niche site. The new items also improve the overall ranking for the site so they help all of the existing items. Another benefit is brand recognition. Quite a bit of my traffic comes from people Googling the name of my site.
Pick a Niche You Enjoy Spending Money In : I'm happy to keep working on my site because it's a little like getting paid to shop. I enjoy researching products that I might want to own. It would probably feel like work to research something I don't care about.
Get Involved in Your Niche : I built up traffic to my site by posting on forums for my niche. I did NOT post links just to promote my site. I got active in the forums by answering questions when I knew the answer or by helping people solve a problem when I knew the solution. Eventually I built my site so that I could post a link that answered the question or solved the problem. My focus on providing value to the community led to people becoming my advocates and promoting my site for me without being asked. These quality forum links are responsible for improving my rankings on search engines. By my fourth month a majority of my traffic was coming from search engines and that's now up to about two-thirds.
Be Patient : My site only earned $2 in its first month and Amazon doesn't pay you until you earn at least $10. When I earned $60 in the second month I didn't get paid right away since Amazon waits two more months before providing payment. Since I spent one month building the site before even launching it that means I worked for five months before receiving my first dollar. I'm glad I didn't give up. Now that I receive substantial payments each month I'm careful to set aside what I think I will need for taxes in a separate account.
Put in the Work : I probably average 2-3 hours per day working on my site. This means I was earning less than minimum wage for my time for the first 7-9 months. But I kept adding products to my site and kept making site improvements and now it is really paying off. I took off the first two weeks of June due to other priorities and still earned over $800. When I spend time on my site I'm not doing it to earn money for the time spent, I'm doing it to give myself a raise by growing my business.
Promote Cheap Accessories : My first two orders were not for products on my site. Instead they were for accessories to those products. It didn't take me long to build on that idea and start adding recommended accessory links. Once someone decides to buy a product they are much more likely to buy a much cheaper accessory for that product. Watch your Amazon orders report for ideas. The lower priced items lead to more orders and more orders lead to higher commission percentages. I went from 4% (month 1) to 6% (month 2) to 6.5% (month 3) to 7% (month 6) and last month to 7.5%. If someone makes a purchase on Amazon with ten items in their cart then that counts as ten orders. Anything they buy within 24 hours of clicking on your link counts as long as they don't click on someone else's link after yours.
Add Expensive Items : Initially my site focused on an affordable type of product in my niche ($50 - $150) but eventually I started adding more expensive products. This turned out to be a great idea. The higher priced items brought in more money per order and took advantage of the higher commission rates from all the orders on the cheaper products. They also attracted customers who were more likely to spend and who were more likely to buy expensive items in general. That helped my site earnings reach four figures per month starting in April. Last month I earned a $175 commission on a $2,300 product that was not even listed on my site (it is now) helping me on my way to nearly $1,500 for the month.
Link the Image and the Price : About 75% of my earnings come from people clicking on the product image (which links to Amazon) or clicking on the product price which is in a paragraph describing the product. Everything else I've tried such as the buy now button and links to accessories only make up a small percentage of the earnings. Be aware that if you have Amazon's price on your site there are a number of rules you must follow which are listed in their affiliate terms and conditions.
Go With Your Strengths : I'm more of a software developer than a writer so I don't actually have any product reviews on my site. You read that right, I have an affiliate site with no product reviews. Instead I built a searchable product catalog that offers many more search options than any other related site. It also has more accurate product specifications than Amazon. As a programmer I was able to use Amazon's product advertising API to automatically update the prices and keep in line with the terms and conditions for showing prices.
Leverage Popularity and Product Comparisons : I have automatically generated pages on my site to show the most popular products. I use my site usage statistics and Amazon's sales rankings in conjunction to calculate the popularity. These pages get a lot of traffic and generate a lot of clicks to Amazon. Popularity may be more influential than a positive review in helping someone decide what to buy. I also automatically show similar products and allow visitors to compare any two products side-by-side. With several thousand products this makes my site nearly infinite in size.
Keep the Search Engines Happy : I submitted my site to Google and Bing and regularly use both of their webmaster tools. These tools provide valuable recommendations for search engine optimization (SEO) to make the site easier for their bots to read and easier to use on mobile devices. I also submitted a sitemap and automatically keep it up-to-date.
You Don't Have to Do Everything : I'm not building an email list (new products in my sub-niche generally aren't available on Amazon so I don't know what I'd promote). I don't get much traffic from social media (I've tried, but half-heartedly). I don't buy traffic (I earn 5-6 cents per user and buying traffic costs a lot more than that so it would have to be REALLY good traffic). Maybe I could earn more if I did those things but I'm very happy with my current progress. Besides, maybe there are some types of site where those things are not appropriate.
I hope anyone still looking for their first online success will find my story encouraging. Best of luck!