I keep private keys with me. And readily load them into either myetherwallet or metamask according to my need.
For long term storage of tokens, I use a single private key for a single token. While my regularly using wallets are used for multiple transactions.
You have a good tactics. I also use the Metamask plugin installed in the internet browser to sign ETH transactions. In addition, I do not store all my ETH coins and ERC20 tokens in the same Ethereum address. I usually divide my funds between different ETH addresses. I store private keys on my computer in a password keeper encrypted with my master password.
The best way is to use an offline Ethereum address generator. Often such an application can compose a new ETH transaction. It is secure and safe.