when do I lift? when do I do cardio?

I've read a bit about this issue and so far what I have learned is this:
If you want to burn fat and lean out do your cardio first then your weights.
If you want to build muscle do 10 min of cardio to get the heart pumping and the blood flowing and then do your weights. Do your cardio afterwards. When you do cardio first you are going to be a bit weaker when it's time to lift but you will burn more calories while lifting. I think it all depends on the look you are going for to with your body and how your metabolism/ body works. We're all different. It is important to constantly challenge your body and change things though. So, one day do more sets, more reps, faster, lighter weight...the next go heavier, less sets and reps but more weight...that kind of thing. This will keep your body guessing and give you great results!
Hope this little bit of info. helps! :)