Onyx is tops.
1. Open the app.
2. You'll be prompted to choose the S.M.A.R.T. status (I think), if your HD is HFS+ (journaled). I don't bother, since I have another app that does that.
3. Then you'll be prompted to do Verify Startup Disk. That takes a while. I don't use it, as my HD is the only drive in my Mac
4. You'll be prompted to enter your password so that Onyx can get into the System.
5. Click Maintenance (the cog wheel)
6. Click Permissions and Execute - this process may take a long time, first time, it may not, depends on the state of the System.
That's all I do. You can choose to clean caches if you wish, also do various other maintenance tasks. You should run Onyx about once a week or ten days, depending on how much you use your Mac. Some people run Onyx once a month, but I think that's too long a time.
