I’ve searched on the internet and still unable to understand the usage of cold storage. Actually, I want to buy a few types of low price crypto currency coins and save them in my personal devices or papers. Later I need to send them to some exchanges to sell at higher price. I don’t want to rely on online sites/firm meanwhile before exchange. Neither I want to download blockchains of each currency.

So, how can I efficiently save my coins in my personal captivity? If I use offline wallet generator, how In-ward and Out-ward transactions will be carried out?