Run lots of Cover 4. Read the #2 receiver on your side, whether thats a Slot WR or a TE on the line. If he runs deep, cover him man-to-man. If he doesn't run deep but runs a shallow, an out, in, slant etc., you fly down to the underneath zone level (i.e. LB/"yellow" zone level) and look to become a Robber and jump any inside route from the outside WR (a post, dig, slant), or anything coming across the field from the other side of the formation. Lots of picks this way.
For the run game, from same Cover 4, as soon as you read that its a run, fly down into the box aggressively and play the run from outside-in (i.e. protect the outside alley 1st, then fold inside toward the "B" gap between OG and OT.
Its true that at times there is much less "action" to be had when playing as a Safety, but once you get used to it i find it more fun than being a LB or DL, as I get to play deep pass coverage as well as play the run.