Where do I go from here?

I'm something of a newbie at the game: I've played quite a bit, but I've never really got a character to "End-Game"... Until now. I've been playing a Dual-Claw Scion build, and have been making my way through Act 3 of Merciless, having just made it to the Map Device.

Unfortunately, I don't really know how to go about increasing my character's potential from here! Obviously, getting better gear, leveling up further, and improving my gems are the obvious way to go, but I'm not really sure what I should be looking for, at this point. Up until now, it's been a quest for more damage, evasion, life, and resists, and more of those would always be nice, but are there other things I should be looking for? With gems, I've only really been using a few: A Dual Strike setup, an Aura linked to Reduced Mana, a curse, and a mobility skill. I've heard folks talk about "Cast when..." support gems, and other stuff to round out the remaining sockets I have, but I'm not really sure what's effective!

My character's gear at the moment is as such:


And a skill tree that looks like this:


I've not really been having trouble in Act 3 Merciless so far, so I think things are working? But I want more power, and don't know where to go!

You farm. Hold off spending more points, perhaps get to Finesse in the ranger area. You can get a monster of boost off of several layers of gear upgrades.
When you get a feel for how strong the build really is I'd grab all available block.