I have to disagree with P. The only part of your flyer that is hard to read is where the yellow shirts are.
Choosing the right background can make or break your flyer. I like the t-shirts as a back ground if you
where having a special on t-shirts but it doesn't go with everything your are trying to get across to your
potential customers.
People are visual creatures and seeing t-shirts they think t-shirts no mater what the description on the page says.
Seeing how you are making a trifold flyer make each part about one particular part of your business.
The front should give as much info about your business as possible in short straight forward parts.
I think you are on the right track with the first and second fold the third fold should have Screen Printing,
Embroidery and Promotional Products with a short description under each heading. A reminder of what is
on the first fold
On the inside you can get into more details. keeping the same theme going with one fold for SP one for emb
and one for signs.