Not enough monitizing. Add some adsenses ads above or below your articles. Social bookmarking widget should be on the bottom of every article, it allows people to bookmark after they read your articles and want to bookmark them. My .02
I don't much care for the colours to be honest. Also, I suggest some photos/graphic to make the site less boring. And honestly I think you'd be better off appealing to peoples pockets. Maybe add a section "Save money by saving the environment" or so. Maybe make a function where people can vote for the best tips. Maybe add a section where people can add their own tips and maybe win something. Good luck.
I just suggest that you will try to change your Logo. header is Really Nice and add some Image Graphics too...
Personal opinion You need some borders or something to brake up the text and a little more colour to the site. Looks like a lot of content needed so good luck with it Cheers Samantha
Once I click on any tip on the left side nav bar it takes me to a page with a different layout and the navigation bar is gone. You need a little more consistency.
hm very good idea .for me it is interesting .but you need more information.the more you have,the better it is