Security Rules
My rules to help you use Salesforce securely.
Save passwords in LastPass or similar
Have a separate user for Integrations.
Use OAuth2 over basic authentication whenever possible.
Give your Salesforce developer a separate login. PLEASE!
Do not enable System Admin privileges for all users.
Yes, that means that all users will NOT be able to create workflows - but this is good.
Check which apps are connecting to your Salesforce regularly. https://help.salesforce.com/htviewhelpdoc?err=1&id=connected_app_monitor.htm&siteLang=en_US
Have a good understanding of Permissions and know which data which users can see in your Org.
Don't install random apps in production unless you know which third party services they are connecting to and why they are connecting to that service.
Bakup your Salesforce regularly.
Configuration - see MavensMate and Git for Non Developers
Data - see Backup