I've a good article (about 500 words, low/med competition and unique content) in my micro blog niche, it's about tech. The article is ranked in first page on Google and have some good PR1 backlinks. It's getting from 1200 to 1500 organic searches per month. This article is a review about a product which is sold on Amazon and it's getting me some money as affiliate from 100-150$ monthly. I've used about 40 different unique keywords (manual work not bots) and it stills ranks well. I've read somewhere here that too many keywords could damage the rank/SEO of the article? Is this really true? To rank better in Google so it's better to use less keywords? Thanks for reading.