Design wise, look for solid colors, or designs with a more vertical print. Horizontals emphasize width. Avoid elastics on the bottom of jerseys. A lot of the jerseys on TE have a contrasting color or print on the sides, and that kind of design is very slimming.
I think most everyone feels self conscious in cycling clothes. There's no where to hide, and a lot of the things that make our rides more comfortable are not very flattering. Who looks good in a padded chamois, I ask?
'02 Eddy Merckx Fuga, Selle An Atomica
'85 Eddy Merckx Professional, Selle An Atomica
'10 Soma Double Cross DC, Selle An Atomica
Slacker on wheels.