Every now and then I post MAC tips and here is a great MAC tip to go into safe mode. The only time I would suggest you go into safe mode is when your computer is having problems so you can do diagnostics.
Info
Step 1 - reboot computer
Step 2 - hold the shift key until the Apple logo appears
Step 3 - release the shift key after the Apple logo
Step 4 - login
Step 5 - when your all done reboot to go back to original computer settings.