I max out the Bloodbound skill first, then put as many points as I can into Focus/Replenish (depending on the level) and Forge.
When I play, I stick with the faster starter gems given (being very conservative). Then after I've saved up a bit, I unlock Bloodbound.
Remember you can go back to earlier levels, so make those first levels as hard as possible to get the most xp from them.
It should also be noted, that you can combine lower-grade gems into higher-grade gems to boost their stats. Their grade won't increase, but those boosted stats will be extremely helpful.
If a certain strategy doesn't work for you, try mixing things up, and find a plan that not only works for you, but works for your mana pool as well. Every map has a way of beating it. And you can try to force it, but try to be creative with your solutions.
Go back, get more xp and levels. Sooner or later you'll have to do that. Get the Wildgem skill ASAP and master it ASAP. Sell the wildgem at the beginning of the battles. This is the ultimate help.
