How to use cold wallet and trade?

I need a little help. Until now i use to buy and sell all on the same platfom(kraken). But deposit and buy sell fees are always kinda high. And then i found out about ex. buy usdc on kraken, sending is to phantom wallet and switching usdc for solana on jupiter swap(only example). Does anyone have experience with this, i would like to hear some advice.

And right now i hold some crypto do i swap it all for usdc. But do i send it to my eth or solana cold wallet. etc. etc.

Thanks in advance for any advice.