I am emb a small logo with text. I'm using Allegro font and the lettering needs to be3/8" high. I'm emb on very light wt Under Armour t-shirts. Does anyone know what the density and pull comp values should be? Where can I find the various values and defaults for these? If you can give me some pointers on how to make this lettering look good without driving myself crazy, any help would be appreciated. Thanks to all of you.

Small lettering is just a satin columns with angles and curves. 

Break down your satin columns this way: 
1 mm to .6 mm use 60 thread and a 65 needle. -.2 density. Use a single run underlay at 1 to 1.2 mm length.
1 mm to 2 mm single run underlay at 1.5 mm and a +.4 density using 40 thread. 
2 mm to 3 mm use a contour underlay at 1.5 mm length. 0 density 40 thread
3 mm to 6 mm use a double zigzag at 15 density for the underlay .0 density or 4.0 master. 

Pull comp will be up to your discretion. I prefer to distort the horizontal and the vertical letters. To do this add more height to the horizontal and less height to the vertical letters. Pull comp only distorts the letters. If you add too much horizontal letters look bulky or angled depending on the font. This is rule of thumb and some exceptions will apply. Substrates and backing and toppings will all have an effect on the threads ability to replicate what your trying to achieve. This is true for all satin columns in a embroidery design. If the font or the satin column doesn't meet this criteria it simply can't be done. I advise clients all the time to change fonts. Just because the font exists doesn't mean it can be sewn. 

Sorry to be so technical but this is my approach to all the designs I do. Many digitizers just give you what you send them without analyzing the art first. Then you have to edit something that shouldn't have been done in the first place. Its better to know up front what your getting into IMO.

I am using Stitch Era .  Is there a way to adjust the column width of the lettering? Hope everyone enjoys a Happy New Year!

Thanks,

You can always blow out the width by adding pull compensation to the lettering.

1-place the uppercase N on the screen

2-copy twice placing them in a row

3-select the first N, Properties, text effects, change the width compensation to 80%

4- select the third N, Properties, text effects, change the width compensation to 120%

5- view the comparisons