Ok, check out this book, Photoshop CS3 for Screenprinters. It was kinda useless to me because I do sim process wherever possible...which has been everything so far, I've yet to have a need to print 4cp, but the 4cp section is thick and looks like a good primer for doing it all out of PS. There's a disc with sample/practice files that go along with the sections. I'd still recommend getting a job sepped out for you. Study the channels from the separator to get a feel for how it's done by someone with experience and consider it an investment. For the cost of seps though, I usually just roll it into the pricing and save myself the time. I do enjoy separation but there's only so much you can do.
I like sim process because it's more forgiving, works over a variety of colors/substrates better and is more repeatable, but if you can do higher end sim you can do 4cp. I would expect to use a bump plate or two for colors that aren't going to reproduce well in cmyk or need to be spot for branding or just to make the art work.
- Don't combine any solid text fills onto the same screen as your halftones, you'll need an extra black screen for instance if there's solid black fills. Very good seps will stack up the cmyk colors to sometimes achieve this but that's trickier.
- Decide if you want to angle each color to achieve a rosette pattern or set them all to 22.5 degrees and go. There's a lot of debate on this I believe but I find the latter to be best on textiles, generally speaking. Regarding the former, there's as many rules for those angles and the print order as there are printers.
- Related to the above, keep in mind you are not only fighting moire from the film to the mesh in this scenario but also interference from the weave of the garment so chose those angles wisely. Have plenty of backup screens in case something goes totally fubar on you.
- On white Ts I'd use a 310/30 or 330/30 mesh at 60lpi at around 22 n/cm. For standard, thicker mesh thread get it up as high as it will go in tension if using retens. If not, just use good screens and keep in mind that lots of high end work is done on static frames everyday, it's just tougher to get it setup and you'll have more of a hand to the finished print.
- Use a good rip for film output and take a second to dial that all in if you haven't already.
A lot of that is probably really obvious but good luck!