Against 1. e4 -- if you like to counterattack, the Sicilian 1...c5. If you want a solid defense, the Caro-Kann 1...c6 or the Petroff 1...e5 2. Nf3 Nf6.
The French 1...e6 is intermediate between counterattack and defense. These are all sound; try them all and see which ones you feel comfortable with.
Against 1. d4, I've never found a defense I really like, so I'll leave it at that.
black
GM David Norwood (who I believe is no longer an active player) used to play 1 g3 in virtually every game as White and 1...g6 in virtually every game as Black. Playing this way over and over might become boring after a while, but after playing tons of games, you'll recognize most of the strategic and tactical themes that occur in the opening and early middlegame.
One of my very favorite opening books is "Winning with the Modern" by Norwood.

I have used the caro-kann against d4 and even c4 with great success
That means that you probably often end up playing a variation of the slav.
I have used the caro-kann against d4 and even c4 with great success
One of my favorite repertoire books is called "Black Defensive System for the Rest of Your Chess Career", by GM Andrew Soltis. In the book, Soltis recommends a Black system based upon pawns on d5 and c6, viz.:
1 e4 c6 2 d4 d5 (Caro-Kann)
1 d4 d5 2 c4 c6 (Slav)
1 c4 c6 followed by ...d5. (Usually transposes into a Slav or Caro-Kann).
The book is out-of-print, but is available at http://www.labatechess.com
does any one know any good openings for black