Morphling's skills (except for Adaptive Strike) are all very versatile in their usage, so the best advice I can give is practice.

You can cast and attack while Waveforming. Combine this with things like the Shotgun combo (Eblade>Adaptive), Teleport scrolls, or jumping to a Replicate.

Morph as much agility as you can, without sinking more than around 200hp below everyone else.