What's the good way to clean up the system (and is Bleachbit safe) on Ubuntu 14.04?

I used Ubuntu 14.04 (Trusty Tahr) for about a year (actually upgraded it from Ubuntu 12.04 (Precise Pangolin)), and during the time I installed some packages, and removed some other packages.

Now I think it's probably time to clean up the system as it's likely several unused stuff is lying out there (both from the old 12.04 and the new 14.04), and I hope to have a cleaner system that works faster.

I found these two links:

• How to clean Ubuntu safely

• Cleaning up Ubuntu 14.10,14.04,13.10 system

Both links seem good, but when I came across to what they said about Bleachbit then one says yes, and one says no - a bit contradicting.

What should be done for this common task?

To remove any packages that aren't needed by the system:

sudo apt-get autoremove

The other answer for this question:

sudo apt-get clean

This just clears the package cache for downloading new packages, it will not uninstall any packages.

See: https://help.ubuntu.com/community/AptGet/Howto

Ubuntu tweak will be to your liking.

It has a "janitor" option where you can clear caches files, delete old kernels, delete orphaned .debs and more like that. But what gets removed tends to be a few MBs of software that is not longer used on your system but will not have interfered with what you normally do.

A crash of kate should be treated as such: search the crash online and see of there is a fix, otherwise you can opt to file a bug report against kate.