I was in a similar situation to you and I would say that diet is more important than anything.

If you don't eat right, you might get stronger through excercise, but never gain any real muscle volume.

Like I did, you probably think that you eat a lot, but if you sit down, do the homework and log what you eat every day, you will probably find that you are practically starving yourself.

I would suggest you find one of the many calorie calculators online, a good diet for building muscle (just getting a lot of calories won't do it, it has to be the right calaries and it has to be balanced) and start following it.

You might find it tough to eat that much at first and you don't have to make the massive jump in calorie intake on day 1 - gradually work up to it.

Once your diet is sorted you will see how much better an muscle building routine goes.