Agree with minimum necessary privileges, but also, in order to avoid accidentally modifying prod instead of dev / test, I find it's useful to use Register Server in SSMS and assign a different status bar color or color family to each sever, depending on the environment. My prod servers have a red status bar -- caution, do not make changes unless deploying; test is orange (since yellow is the default); dev is green.  A server that doesn't neatly fit these categories might be cyan.  It's not a foolproof system -- assigning colors per DB instead of per-server would help me -- but combined with moving the status bar to the top of the widow, it makes it very easy to know at a glance which server the current SSMS tab is connected to.