Most of the SEO you need to know is on record in plenty of products. However, all of the best SEO in the world counts for squat if your article stinks. I'd be very wary about outsourcing articles -- there are far more bad writers than there are good ones.
1. If you are "bum marketing", then don't go for the damn silly keywords. It is far better to select 10 good, catchy and searched-for keywords than 100 bad ones.
2. Write an article which actually has the potential to lead to a sale. In Desperate Buyers Only, the author explained how she had penned an article about getting out of the NoChex system and submitted it to EA. I believe the article was a fairly meaty 800+ words, and is still available online if you look around. That particular article is a good model to follow, because it checks all the boxes: it is substantial, it targets a desperate market, it is well-written, and a solution is provided in the resource box. Notice how she still gives value in the article; many articles provide NO real value.
Ultimately though, one of the major ways to get great traffic from articles: hand submit them to niche sites. These places are always looking for fresh, substantial and -- preferably -- exclusive content. It's a fair trade: they get top content for free, you get a good backlink back to your site, as well as your article being placed in front of your target audience.