Try to do what madkow said - you can probably leave off the multimeter part for now since you're able to get prints (even if they don't look so hot right now) and wait to try it until you have a ceramic screwdriver and you may not need it ever - most of us do it by feel/sound and get better results (still using the screwdriver - ask later).
Get these essential tools:
Link to ceramic screwdriver: http://www.ultibots.com/ceramic-screwdriver/
Digital Calipers (yes, harbor freight is acceptable quality for 3D printer stuff): http://www.harborfreight.com/6-in-digit … 68304.html Get the one that can do both metric and SAE - it's worth the extra $1.
I'm assuming you're on a 5/16" Z-screw so...
First, Use the calipers to accurately determine your Z-steps (ask later when you get your calipers if you're not sure how to do this).
Second, I would go to the Prusa Calculator (http://www.prusaprinters.org/calculator/) and get the "optimal layer height for your z axis".
Instead of 0.3mm use 0.2963mm
Instead of 0.2mm use 0.1976mm
Instead of 0.1mm use 0.09878mm
This is so your stepper motor can use full steps and maintain accuracy while it's not moving - do it - your layer height and overall accuracy will improve. ***Use one of these or a multiple of one of these for every Z movement in Slic3r including layer heights and any z-lift you want to use.
Third, set ALL of your extrusion widths to 1.2*nozzle_diameter, print a single walled cube (search or ask), measure the width of the wall with the calipers, and accurately set your filament diameter as follows:
((measured wall width)/(1.2*nozzle diameter))*(current filament diameter in slic3r).
Report back and we'll keep helping.
SD3, RUMBA, 360W power, ABS: Glass bed + Aquanet Extra Super Hold Hairspray, Anti-backlash Z spanner, Repetier Host + Slic3r