Her shunpo resets when she picks up a dagger and you want to avoid locations where her daggers land. Her dagger lands the opposite side of the first target hit and she can also shunpo to a close location, champion, or dagger. If it's not a dagger she'll be picking up, her shunpo gets placed on CD. That's an engage opporutnity of about 8 seconds.
Her weakness is CC. She will feed against anyone who plays Ryze(if you last the 10-15 minutes of farming you need. Just an RoA on Ryze and a Tear will destroy her).
Don't let her roam to bot for kills. Punish her for trying to farm. Poke her out.
Engage on her when you have SS or she can outplay you quite easily.
She falls off really hard late game(30-40 minutes if you farmed at least 250-300 CS).