Windrunner can be played in so many different roles it's hard to tell you good items for her. She's one of THE most versatile heroes in the game which is why you see her picked so often in competitive play.
I prefer Phase Boots on all builds of Windrunner. They can help you chase up to someone to land the Shackle to secure a kill, and combined with Windrun it makes you really hard to catch as well. Also gives you a good chunk of damage on your ultimate. If you are having a rough game, Strength Treads can help you stay alive a bit, but generally I go Phase.
She can be played as support, where you pick up Mekansm/Pipe if your other supports can't manage (WR tends to get good farm). Force Staff is also frequently picked up for its utility. I like Eul's since its cheap and gives you enough mana regen to spam your spells. If you're doing well, Sheepstick is a great choice.
WR doesn't need too much in terms of survival since her skills are long range. Force Staff with Windrun lets you get out of a lot of hairy situations. If those two can't get you out of the trouble, it's fairly unlikely that anything else would. If you have Eul's... even more fun.
I never really play carry Windrunner -- it's extremely rare in pubs not to have a better carry than WR on your team. Diffusal Blade is hilarious on Focus Fire but... yeah, don't have much advice for this.
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No amount of planning will ever replace dumb luck.