Yes, it is hard to play the opening if you don't know what middle game goals to aim for. I would start with a book on pawn structures. Drazen Marovic's Understanding Pawn Play in Chess is good.
http://www.amazon.com/Understanding-Pawn-Chess-Drazen-Marovic/dp/1901983315
I'm noticing in a lot of my games, especially during a current OTB tournament and here online that I can keep equality until about the 10-15 move mark. I'm wondering now if maybe I should look into some reading material(books) on the midddle game since it seems to be there that everthing starts to fall apart. Anyone have tips or book suggestions ? And yes I'm still practising tactics.
EDITED: I previously wrote I can't keep equality....
I meant to say I can keep equality so my openings are usually sound.