here's what I do:
- kill as many enemies as you can as early as you can, every bit of experience and gold helps
- use the terrain to your advantage, enemies that can't jump are easy prey if you find the right spot and basically give you free exp
- collect as many items as you possibly can, getting something like Infusion or Golden Gun early helps a lot
- learn the layout of the map, the locations of items may change but the terrain doesn't (yet)