No traffic to website

Hi guys, I need help here. I have a site that's about 2 plus months old and someone already started the SEO on it. Now, that person left and placed all of the heavy work on me, all these SEO stuff. I'm still on the process of understanding the Tiered Backlink strategy and I'm continuously studying to make my own checklist or "to do" list. About a month ago the website had traffic on it even just a little bit, but now it just drop into nothing! It's been 2 weeks since this happened. I've been checking our Google Analytics, i've been doing web 2.0's, social bookmarking, and social media for tier 1, but still no effect. Anyone can help me? I'd greatly appreciate it.