How does it work?

Start with Cloth Armor and 5 pots, take her Q first. Go beat up Wolves and use Q to store spider charges. Once you've taken down Wolves and Waiths you should be Lv 2 and will take W. After that she can clear with awesome speed by popping her W with her spiders to back you up. Once you hit 3 you can use her E stun to gank lanes with her W/Q in human form (shifting to spider form if needed).

After level 3 she's a pretty standard jungler, just get gold for your build and help secure lane advantage for your team.