Altering t-shirts and design question

[ncbyrne]

I would like to make creative t-shirts for myself and my DGDs for our trip in late August. I know it will be hot so I'd like to alter some store bought t-shirts by cutting off the arms and maybe even making a scoop or v neck. Any tips on how to do this, and then what type of design would look good - and should I put it on the front, back, or both?