I love her. Her playstyle is right up my alley: Fast paced and disruptive with very high mobility.
The way I play her is to stay in the sidelines and take alternate routes. You want to stay invisible as much as possible, and random damage from big battles can reveal you to the enemy team. The translocator is great for getting to hard to reach spots or taking shortcuts. Your priority is to pick off low health targets and hack health packs. Hack single enemies when their abilities become a nuisance to your team (Roadhog blocking a chokepoint and healing himself, for example), otherwise it's not worth the time and risk.
So basically: Stay out of big battles, move invisibly through flanking routes, hack health packs (especially the large ones), choose your fights and pick off low health targets. Hack enemies that are bullying your team with abilities.