hi. (old t shirts)

[xblackxeyesx.livejournal.com]

i'm new here. i dont know if this is the right place to ask my question but i'll go for it. its about re-sizing old t shirts. i was wondering if any of you girls knew an accurate way to re size an XL guys shirt to like a Medium in guys. is it possible? or should i just get them altered professionally? let me know what you think.
thank you in advance.
xxx
courtney