How to improve strategy?

I'm pretty new to chess, but i know the fundamentals. In almost every game after the opening or a little into mid game, i can't come up with a move. It just seems as if moving any pieces won't do anything, even though i know this is not the case. Is this lack of strategy or tacitcs, or both?

This is a lack of plan.When you get stuck after the opening,just try to improve your position,your minor pieces etc.You need to have some sort of idea about what you want to do.

It sounds like a lack of knowing what to do. 

I say this in a lot of threads, but I'd suggest reading Jeremy Silman's books about the imbalances (such as How to Reassess Your Chess).  They're really helpful for understand the position, and finding a general plan for activity. 

He knows what to do:  Learn how to come up with a strategy.

After the opening game, figure out the imbalances. Most of the imbalances are long term, so true with strategy. By learning imbalances alone, you can come up with a simple and yet effective plan/strategy.  Practice a lot of tactics to improve your tactical vision. Pattern recognition helps a lot! 

When I lost a game, i tried to figure out where did I made the mistake. And I try to pinpoint 1 or 2 best moves to improve my bad positions. In this way, I can improve slowly.

I can reccomend another book, Sierawan's Winning Chess Stratagies.  I thought it was helpful.