Since this is your main account, you could always PvM. I find it one of the only things worth doing in Runescape. Get 80 Dungeoneering, 92 Herblore, 95 Prayer, and max your combat stats; then you'll be a PvM beast.
For PK, I'd say the best option is to max all of your stats. Since your Defense is so high, the only PvP you'll ever really be able to engage in is the low-risk whip/gs/rapier PKing in Edgeville, or the high-risk maxed hybridding in the deep Wilderness. The latter is where all the skill is at, anyway.