- Quality: Be sure the fabric of the shirt is not flimsy or semi-transparent. A quality heavyweight t-shirt can not be accomplished with a thin cotton weave. Be sure that the neck, shoulder seams and hem line have double-needle stitching and that the neck band is not wavy. The body of the shirt should have seam lines that hang straight down from the arm pits to the lower hem.
- Fit: Depending on the style of the tee, you should generally be able to raise your arms without showing your stomach or back. Short sleeve T-shirts for men should have sleeves that hit just above the bend of the elbow. The body of the shirt should be slightly roomy, not stretched across your chest or stomach. The armpit seams should not cut into your arms but also not hang down more than an inch or so.
- Prints: If you are shopping for a screen-print or possibly a larger back print on a t-shirt, look for the softer feel of the print. If the back print is large, you don't want it to feel board-y or stiff. It should not crack or peel off after washing. If you go for a band print, it should be printed on both the front and back to achieve the best quality look. Mini-bands should not bee too large, taking up less than 3 inches vertically. Otherwise they do not really qualify as a mini-band, do they?
- Price: Ultimately, you get what you pay for. If you compare prices and find that there is a "heavyweight" tee that costs a fourth of all the others that you have compared, beware. Make sure that you can return it if anything goes wrong and ask about shrinkage and fading.
The best heavyweight t-shirts that are available out there right now are custom made and have a full 10 oz cotton weave. Make sure you are not getting a knock-off.