OK, thanks a lot for the advice.
I was running through a few things on PT last night and noticed that the majority of my losses, nearly 75%, have come from multi-way pots, which probably fits in nicely with what has been pointed out that I call too much instead of raising my hands.
I also lose a lot of money from the blinds, especially BB. I don't know whether this is because I am folding too much, or I am calling too much because I get a "discount". Will have to keep an eye on it.