I am a 1st grade teacher.  I love making new shirts using my Cricut.  All of the shirts were made with heat transfer vinyl using a heat press (highly recommended).  I also recommend turning your shirts inside out to wash and hanging them to dry so the vinyl won't age/crack too soon.  More than likely, your vinyl will eventually crack or it can come off if you put the shirts in the dryer.  I refresh my shirts quickly in the dryer if they are really wrinkled.  I also recommend making sure shirts that are layered are sliced first so there won't be so many layers on top of one another.  

Aqua blue shirt from Bella+ Canvas & svg file from Etsy

What a beautiful color this mint green Bella + Canvas shirt was!

This shirt turned out beautiful.  The sparkly blue Siser HTV is my favorite.  I got this from Craft Vinyl.  You must read the rules if you are going to buy from here.  I bought the mint green htv from Michaels, and ordered the black htv from Amazon.
    

These Next Level shirts are so soft and comfy.  I ordered them from www.jiffyshirts.com.