How do you use PPC for content sites?

Hi guys.
I created my first website called www.1printer-supply.com. It was intended to be an informational site. I want to experiment with Google pay per click advertisement and I would like to ask you guys about the best and safest approach in pay per click for content sites.

I mean, as organic search engine placement or SEO comes to question, everybody knows that content on the website is king. But what about with PPC? How do you compete with sites that directly sell their product and obviously can afford a much higher bid price than you, who might only promote affiliate programs or participate in Google adsense?


Second how do you track the ROI if you don’t directly sell your products?
May be with tracking newsletter sign ups and clicks on particular links?

I’ve obviously got to pay less for a visit than what it's worth to me but how can I determine that? May be with lots of experiment?

Thank you for looking my question, hopefully everybody will benefit from it.
Laz the printer guide.