How to avoid stringing?
I've been able to reduce stringing by reducing the nozzle temp in 2°C increments until it goes away.
You'll also want to increase your retraction settings a bit.

The problem is caused by the plastic being too hot and oozing out of the nozzle - it's a bit too runny.

Search Thingiverse for Heat Towers.  You'll need to edit the G-code so that your printer adjusts the nozzle temp at each layer.  That will give you a really good indication of the best temperature for the given material.

Keep in mind you'll want to print it for each new brand (and sometimes color) of filament.