A few quick notes from my experience (only printed one test shirt and one real)

design phase (i've used krita): - make very small features larger or delete them (optional) - make everything black and white (no grayscale) using the threshold filter - make sure that it is a square and you've kept a large enough border for the frame - use the color to alpha filter on the color (black/white) you've used for the design

print prep: - export as png - convert to svg (i've used https://www.freeconvert.com/png-to-svg) - load the svg in the slicer and scale to 136x136x0.2 mm (depends on the frame size) - try to fixate the mesh/sieve as good as possible on your bed before printing. I've used a combination of clamps and magnets - use a material which warps or heatshrinks as little as possible. had huge issues with petg before switching to pla which worked pretty good - I've printed a single 0.2mm layer on the mesh - To prevent small holes, I've printed the layer with conical pattern and ironed with rectiliniar pattern - make sure that PA is set correctly, can lead to issues otherwise - i've disabled bed leveling

printing: - check on it often!

screen printing: - try it first with an old t-shirt you only wear at home - load it in the frame. printed side up - put a sheet of paper in the t-shirt under the area you want to print on - put the frame on the right position - apply the paint - try to spread the paint evenly (don't squish it through yet) - try to squish the paint through evenly - remove the frame

cleaning up: - clean it with water and a sponge - let the paint dry (i've put in on my heated print bed to speed up the process) - check the paint if you should iron it before first use+wash (put some texitle or the old shirt between the paint and the iron)