So I got a Trezor to store BTC and Dash, but i wanted to buy some LiteCoin and Ripple

I see the Electrum wallet but it would be installed on my computer.

So my question is, do i have to get a new computer that has never been online before to store Litecoin?
download the wallet on a USb and then install on the new comp?

sorry for the newbie question

Was wondering the same thing about all of these other alt coins (ripple etc) how would I store them safely offline?
Or is there no need to? I dont feel safe leaving them on my laptop