With my home embroidery machine I don't have a problem with thread tension. But since I'm pretty new with my commercial machine, how do I even know if my thread tension is wrong if I can't tell if it's set right in the first place?

[ScottyStitches]

i run 2 inch long samples on each head and each color at one time. the back of the sew should be in thirds. too much bobin on bottom of sew means its too tight on top or bobbin is too loose & visa versa.
also different kinds of material call for different tensions and speeds.
get a subscription to a few embroidery mags and websites.they help more than you can imagine.it's how i learned most of what i know.
oh yeah TRADE SHOWS!!!! get to them.

Hello ScottyStitches and thanks for the tip, but can you or anyone else please provide more details on the samples you're referring to? I'm such a newbie :confused! Thank you!

[ScottyStitches]

this will help you...
http://www.sews.com/tips/oesd/tipsoesd.html