Here's one way to play her...

If playing her in lane, I like to start with a swift shooter to help her with last hitting. It synergises well with her target lock as it lets you switch to the enemy laner more quickly if you want to give them a face full of forward barrage.

Frostburn is a very good item on her, makes it much easier to stick to people with forward barrage and you can use it to catch people who are out of basic attack range. Upgrading that swift shooter into an alternating current is nice for giving her basic attacks a little more oomph and has the bonus of slowing them too because you already have frostburn.

Besides boots, I'd recommend 2 defence items because unlike other ranged heroes who prefer to stay at the edge of fights, she's a very in your face hero. It's easier to run 1 defensive item if you're going against skill shot comps like Celeste + Joule because you're good at dodging, but otherwise I recommend two defensive items. That being said, if you're feeling confident you could try making substituting one defensive item with Eve.

For the third offensive item, I personally really like Sorrowblade because not only does she have 190% weapon ratio on forward barrage, it buffs her basic attack considerably, makes it hard for the enemy team to defend against you and has good synergy with alternating current which gave you +40% attack speed. Since this build doesn't (always) have an Eve it's usually good to have a fountain as one of your defensive items, but since you'd be going for basic attack power too then you don't need to worry too much about energy. Just be conservative with using your abilities on minions and buy potions when needed and you'll never run out of energy.