What you're describing as crusties sounds like material continuing to ooze from the nozzle as the printer leaves a solid surface and moves across an open space to a new location on the print. It's typically due to some combination of too high of a hot end temperature and too little retraction. Your temperature already seems reasonable, so retraction would be an area to pursue. Addition of a print cooling fan if you don't have one would also likely help "freeze" the filament as the nozzle moves away from the solid surface.

On tuning, these come to mind -

There's a start at a print pictorial in the reprap wiki at http://reprap.org/wiki/Print_Trouble...ictorial_Guide. Unfortunately it's incomplete and most of the prints were foolishly done with white filament, which is arguably the worst color to use if trying to photo print flaws.

Triffid Hunter is generally known as a 3D printing guru; his calibration how-to is at http://reprap.org/wiki/Triffid_Hunte...ibration_Guide. You've likely already done much of this, but Triffid does get into detail on fine tuning the extrusion and temperature settings. (Disclaimer: I have not followed this procedure myself)

Tuning could be argued as a combination of slicer settings and printer motion control settings (jerk, acceleration, etc.). I learned a lot about slicer settings through trial and error in attempting prints of the Make: 2015 Shoot Out Test Models. These have the advantage that the models are fairly small and don't require a lot of filament, enabling trial and error on throw-away prints. Each model also tends to focus on just one area of settings (like the fine positive space features model relies heavily on retraction), rather than the overall combination of all settings. In other words, you're troubleshooting one area at a time with these models.

My attempt at addressing the Marlin motion control settings is available at Marlin Motion Related Configuration.h Settings for MakerFarm i3v. It doesn't state "just use the following settings and you're golden", but it should help provide an overview of the settings, along with homework type experiments that would help build a feel for what the settings are, and what might work best for your printer.