If you are looking at honcast and find any 5v5 tactics what is wrong with you? :P
Look at the pro matches and you can see the tactics, usually they pick good teams, use teamplay, look at their ward placement. Then try to think about why they do the things they do and even look at what they maybe did wrong.
Allmost forgot, look at your own matches!
Really important, analyze why you lost.
I could use this aswell, but mostly about picks/synergy.
I'm playing with my friends very often, and most of the time we wreck the opponent, but sometimes we get outpicked/bad-synergy in our team and that makes us lose teamfights. So a small guide about picks/team-roles who synergy well, tempest/behe for example (we instagibbed some teams with those 2 :P).