When I was a kid I liked to play openings like the Benkö, Budapest... But when I faced stronger opponents I got crushed in every (side)line. It seemed that I didn´t have a clue what was going on.
So at a bright moment I bought "Andrew Soltis - Black Defensive System For The Rest Of Your Chess Career". It involves a system, c6 and d5 against every possible line. Slav against d4, Caro Kann Nd7 variation, solid lines against the English, Bird, BDG etc...
It gave me equal positions, because I knew what was going on on the board. I found out that I could beat people of my own strength because I knew what to play in the early middlegames. And after some time when my technique improved I could keep up with stronger players.
In the meantime I bought "Soltis - Winning with 1 c4, a complete opening system", which usually gave me a slight advantage. (You can find them in ebook format on the internet if you want to have a look, just google it)
So my theory is: play what you UNDERSTAND, don´t be affraid to get an equal position, rely on your technique and you should improve quickly.
Hey SchachMatt
Thanks for the book recommendations, you've got me googling these books now.
Are you sure that Chris Ward's book - "Play the Queen's Gambit" is a repertoire book for Black? From my googling it looks like a repertoire book for White.
That is most definitely a book for white. I've got it on my shelf.
Thanks for letting me know.