Try apt-get autoremove every now and then
Tell a new "Linux Mint user" who has stated he's operating from within the context of "Software Manager", tell 'em to mumblety sudo -magicky get...
Dear mmtt22, I'm only a few weeks ahead of you, in terms of the "learning curve".
I'm still dual-booting between WinXP and various debian-based distros.
Here's what I've discovered is helpful (cough, necessary) in terms of housekeeping:
Read its thorough docs to understand what (what all) it can do for you.
Bleachbit is the linux-equivalent to the windows CCleaner utility.
Although it's powerful, you'll still want to use its "shred folders" and "shred files" dialog panes to setup "custom" file and folder locations that you'd like to see cleaned. Like CCleaner, although bleachbit automatically finds paths for well-known browsers, and presents a checkbox for each found browser's cache directory... if you use Midori, or other not-well-known (!) browser, you'll need to specify a custom shred path for its cache.
^--- Note: Many of the files you delete (send to trash) while in "sudo root" role, will be untouchable by bleachbit unless you choose "run Bleachbit as root" from the application menu.
Next on my list of essential (IMO) housekeeping helpers is the app/package named "localepurge".
Cumulatively, across the thousand+ packages preinstalled in a distro, along with each package you install, thousands upon thousands of useless (to you) translation files get installed. Although each is tiny (prob only 2kb to 30kb or so)... they bog your search (catfish, e.g., searching needlessly through these myriad extra files) and their bloat affects the size (and speed) of your backup. After you install localepurge (and configure it to only keep English, en_us, en_UTF8 and whatever few other languages you and your family might speak) it will be registered as everpresent a "post install" step, automatically called each time you install or upgrade any package. From the commandline, on first run, you can expect that it will weed out 70-90Mb worth of of clutter.
Bleachbit may overlap, it might also handle locale files. Still, I'm keeping localepurge installed as well. Oh, there's another package named "sweeper"; naw, don't bother with that -- bleachbit handles everything (and a lot more) than sweeper does.
Mint is playing "Ubuntu wannabe" -- catering to users who want/need to have apps spoonfed to them. The likely intent is to eventually Paypal-enable (or GoogleWallet, ala KDE) the interface, as Ubuntu has done... offering non-free "apps" intermixed with the free+opensource content. Okay, whatever, 'cept it chapped my hide to (almost) install some dang game, called 'rocksndiamonds', without realizing it was not a free app. To anyone considering downloading via Software Manager -- consider: Who's the author of a given "app"? Is support available? Are these "apps" vetted? I might "browse" via software manager, then install an interesting app via synaptic package manager -OR- I might install-and-testdrive using a live USB pen session... but otherwise this venue certainly isn't my cuppa tea.
One step removed is the "community } software" section of the linuxmint site. From that venue, at least you have the benefit of seeing browser statusbar (and whatnot). Install is similarly transparent (the links are apturl:// and are handled automatically to accomplish a spoonfed install). To date, I haven't been able to understand why the "numbers don't match up" comparing the number of, say, "games" category apps -- wildly differing counts are shown, between what you see via the (castrated, chromeless) "Software Manager" interface vs the counts presented at the community site. Does "Software Manager" really consider what EXACT (Debian + xfce) Mint distro I have installed, and only presents "apps" shich are suitable for my system? No, I don't believe it's that sophisticated; besides, for a given software category, SM often shows more titles available than does the community webpage interface.
Anyhow, relevant to houskeeping, be aware that "Software Manager" downloads, and caches on your system, gobs (thousands) of icons. These are are NOT cached to a browser cache directory; find the path (IDK offhand) and weed them out prior to backup, eh?
As a next step, I would suggest browsing your filesystem to:
^--- (brace yourself. careful not to fall outa your chair!)
Right-click and check the size of each of these.
Yeah, weed out any iconsets that you're not going to use.
Because so many different apps default to using "oxygen", I installed that (hmm, or was it preinstalled?)... but I sure as heck didn't keep all the nested "oxy-yellow", "oxy-midblue", etc variants. Insane! Icon sets ship with 9 copies each (various sizes) of seemingly hundreds of "well known" apps (apps I'll probably never install, regardless what iconset I've chosen!).
Hopefully someone else will chime in. What other "likely suspect" paths should we should keep an eye one?