(Re)partitioning for desktops

Things to remember ... And I talk of MBR-based things, not LVM (but see 'monumental' guide here)  or whatever else.

We, desktop-using amateurs, do not do partitioning very often. So it seems to be every time a forgotten mysterious thing and errors are easy to come.
When I repartitioned my sdb, I found myself a bit lost couple of times. Following are some facts and philosophies of a Big rePartitioning. (And it's not a guide 'how big I should make my root and home and should I make separate var'. Do google for that.)

- There can be only four primary partitions per physical disk. After the last one is used, you can not create any new partitions! So, use them wisely... at least the last one should house your extended partition (which then contains logicals). Logicals have limit too, but it's a lot bigger - no practical worries here.
- It's not wise to partition your disk - in a extencive way - from installed distro. There are limitations - things you simply can't do. Use Live USB. Any distro with Gparted (probably the best partition manager) will do. Or, if you want to have all the best dedicated tools - Parted Magic Live USB is your choice.
- You don't need primaries for Linux - it can live nicely on extended/logical. But BSD, for example, requires primary for installation. So does Windows...
Logicals start with number 5... means, when you have only one big extended, then your first distro sits on sdx5. Then there is a swap and you add couple of distros, and/or put your homes onto separate parts... and very soon you end up with numbers in tens... and those beginning with 1 are listed before 5 too. Which looks silly.
- ext4 is complitely ok for everyday desktop Linux use. No need for btrfs, reiser, xfs et cetera - one day it can create a problem (having a bunch of mixed filesystems).
- When repartitioning - if you have spare OTHER disk, archive/copy everything onto it. And delete old partitions. It's dramatically more time-consuming to move partitions, than to delete / create new ones. The difference is tens of times.
- Make a plan. What goes first, what comes later, how big you want all those parts. Remaking them afterwards takes again a lot of time.

A week ago I rearranged all my ten-plus partitions:
- I put my two mainstay distros onto first two primaries,
- And made third primary for future BSD testing.
- Fourth contains extended/logicals with all my other Linux partitions:
Swap is first. 'Common' is second - for all distros to keep various user-files on. It kinda replaces separate homes. Configs stay in their proper places, and are only (partially) back-upped to Common.
And then come different distros I play with. Plus unallocated area for new logicals.

- PS! I also have ext4 partition on different HDD, for real backup, like whole distro backups with fsarchiver. I have this partitions' copy also on external HDD (yes, I have experienced hard disks stopping to work, all of sudden).
For how-to backup with fsarchiver, and how-to get distros work again in new homes, look here.

What I want to say with this short and general post, is: when all those wildly happened partitions turn really bothersome and unconvinient; make a plan according to your needs, think it over, and remake your partitions, hopefully in future-proof way.
And do not forget about backups! Well, after first-time manual reinstall (3-4 hours confing versus fsarchiver 10 minutes) - it tends to be easier to remember.