A few tips and thoughts on finding affiliate programs to promote come to mind:
1. Google It – this one isn’t rocket science but it does work. If you have a Beauty Product blog google “Beauty Products Affiliate Program”. Insert your main keywords into that search and you may just find products that are relevant to your niche.
2. Look at Your Competition – what products are other people promoting in your niche. Quite often a quick glance down the sidebar of another successful blog in your niche to see what products and services they are promoting will reveal affiliate products you could promote to (and it could also point you to some relevant advertisers to promote).
3. Check out AdSense Ads – many of the AdSense ads appearing besides Google search results, on other blogs and even on your own blog are likely to be products with affiliate programs attached. Don’t click the ads on your own blog but checking out what the ads promote can reveal all kinds of potential affiliate partners. The same thing is true with other types of advertising. For example I was recently surfing on Facebook and saw an ad relevant for my blog – on clicking it I found a new product with an affiliate program that I’d not heard of before.