I usually go to M-U to browse for new manga. Summary (including tags for those without much written there) and art for first impressions coz at M-U they are right there side by side. Then I check to see whether it is completed (and fully scanlated). If not, I check to see if the scanlations are regular and up to date. If all of those check out, then I glance at the rating and reviews to get a feel for what others think of it. But usually if something has attracted me from the summary, tags, etc, I'd give it a shot even if it didn't get such great reviews from everyone. And the reverse is also true.