Raising pre-flop limpers when in good position

[QuikSand]

I'm trying to learn to be a bit more aggressive with good (but not great) hands per-flop. I feel I am probably calling with a number of hands when raising would be a better play. (At a few different levels on PokerTracker, I am showing right around an 8% PFR)

In a few other threads here, I have seen mention of pre-flop raises with hands that I'm "borderline" about (and frequently just call, rather than raise). I am used to playing hands like A9s, ATo, KTs, and QJs from late position, but I don't think I raise with them frequently enough against large fields (say, three or four limpers ahead of me). I may have a similar issue with middle pairs like 77-99, though the logic may be different, I guess. I have the sense that I'm missing some good raising opportunities by doing so. (I suspect I'm falling prey to the fear that someone out there might well have any of these hands dominated, so I'm reluctant to push them...)


Can someone either offer some general though on the value of raising hands like this, or alternatively, suggest a book where this topic is detailed particuarly well?