First thing you’ll want to do is to have a backup! I recommend using romdump or nandroid to do this. I think it is better to do this before doing any customization to your phone, including setting up your google account, so that nothing can change your backup.(Even though only the userdata partition should be editable in the phone and hold your information effectively.)
Both of these tools extract all the content from the important partitions on your device(boot, recovery and system), which make up the ‘rom’ of the device.
You’ll probably need to root your phone (AFAIK) and install a terminal emulator. I think ADB(toolset available in the android sdk which can operate directly to the phone, including a shell, when the device is in debug mode) is not enough. I installed ConnectBot. The pity is that this program is best used with the physical keyboard since the virtual one overlaps your active prompt. But the orientation of the app is landscape mode and the physical keyboard is not. Kind of a pain.
I did my rooting with z4root, temporarily. z4root, in root mode, can also reroot or unroot your phone(just for the record).
The system partition is tarred normally, and so it’s ease to extract. Boot and recovery images are a datafile compose of the kernel, ramdisk and some additional information. It can be split with certain linux tools.
I then setup my google account, installed Titanium Backup(which needs root to work) and backed up again. It’s nice it updates your busybox version to a stable one. I find this program overrated. It does only backup userspace apps, not system installed ones. But it’s great to remove unwanted system apps, which I’ll describe next.
The phone comes with Flashback, SHOP4APPS and Phone Portal(or similar), all of them motorola cpu hogging applications.
Flashback records and shows your and your contacts activities, including calls, messages, faceboot updates, etc. Shopp4apps is a market replacement(?) which is totally useless and Phone Portal provides interactivity to the Motorola PC Tools.. I think.
I, of course, removed those apps.
The only customization I really recommend doing, just for the sake of usability, is installing Launcher Pro, which is free and allows great improvement and customization of your launch screen.