generic keywords tend to have high search volumes, but they also tend to have high competition or low buyer intent. They're good to target as part of your overall strategy (just don't try to compete on PPC campaigns). Long-tail keywords, like "Fat loss for mothers" are generally more specific, have higher buyer intent and could be effective drivers of traffic to your site. =) They should be the primary focus for your SEO and marketing.
Once you do move forward, don't resort to simply throwing up a handful of banner ads and call it good. All successful content-driven affiliates will tell you that deep integration of your marketing into your content is the most successful strategy, most of which can be accomplished by looking for affiliate tools outside of the quintessential and tired banner ad.
Don’t just hope and pray that visitors will buy; setup everything correctly and make it happen! If you think that visitors will click on your affiliate links and buy just because you placed dozens of affiliate links on your website then you are wrong! You need to have a structured plan in place. Affiliate marketing is a business so you will have a much better chance of succeeding if you treat it like one.