Reiterating some of what's been said:
"Vintage" soft prints are one of the most popular things we do. Rutland M3, 230 mesh, sharp medium squeegees. 1 flood, 1 fast stroke. If you need a slight bump in opacity, do 2 strokes. If you want to keep colors as accurate (albeit muted) as possible, don't add base. Otherwise, you can add the soft hand base of your choice to make the print as soft as possible.
Also, you can print an underbase the same way, flash once, and top it, and you'll get a brighter print that's still fairly soft.
But here's the thing to remember, counter-intuitive though it may be: Don't try to matte down the fibers on these prints. If you've got enough ink on the shirt to hold them flat, you've got too much ink on there. For this style of printing, most of the time we don't even fully clear the screen.
Also, at least if you do it this way, it is possible the end user will get a little bit of dulling in the print after washing, due to fibrillation. We try to let our customers know to expect this as a characteristic of "vintage" prints. (No one has ever complained.)
Last but not least! Watch your dryer temps & shirts like crazy, do some tests before you do the run. In particular, Next Level triblend has given us terrible problems with discoloration/scorching/shrinking this year.