Configure start-up mode of your cluster SQL Services to Manual.

Try not to place user data on Primary File-group.

If you are using Fill Factor don’t forget to enable Pad Index.

Change the recovery model of your databases to SIMPLE where you don’t need point in time recovery and don’t wish to configure Transaction log backups also (Testing Databases etc.)

If you have to use Profiler on your production SQL Servers – filter as much as you can, configure profiler from a remote machine and do not save the profiler trace on the same production box. Rather prefer using server-side trace.
Note: Profiler is deprecated now, start using Extended Events – they are very light weight.

Rebuild can certainly remove Fragmentation but if the page count is less than 1000 pages, Rebuild is not required.

Configure your anti-virus to exclude all your Database related files namely (mdf, ndf, ldf, trn, bak, log, tuf and other files)

Keep Guest account disabled for all your User Databases.