Here's where I'll start, with a Pershing that's been on my shelf and screwed with for about 14 years.
It came with the old open PCB TX-13 board and was at best a nightmare and at worst a start for a scale shelf queen.

All work on all tanks will begin with separating the upper and lower hulls.
Remove all extraneous features from the upper hull as they are more easily refitted after being removed properly than trying to put them back after they've been broken off. This will also clear the way for detailing and attaching optional peripherals.
You will find that most are attached by posts glued into holes in the hull. You will break some of these and we'll show a new way that you can re-attach them if this does happen in the top hull tutorial later.
In anticipation of this event, acquire some pin vises and some small drills. 1.5mm to 3mm in as many graduations as you can afford.
A Dremel and the basic bits is also a REALLY handy thing to have.

The number of screws and their location will vary but in some cases this can be a little bit complicated.
On some models you will have to remove the tracks.
Generally after doing this for the first time you'll identify the key points and use these only. Some experienced modellers use magnetic catches or spring catches to re-attach the upper hull.
You can explore this but for the moment find 6-8 key screws and use these. You will be splitting the hulls VERY often as you learn and test all of your new found magic.

PRO TIP #1 Never use an electric driver, the speed and friction will soften the plastic and you will strip screws easily, to re insert properly, insert the screw and back around until you feel a "tick" this is the beginning of the original thread and then load down and you'll find the screws will thread in evenly and clean.

PRO TIP #2 drop a bit of CA (a minute amount) down the female screw posts to reinforce them. Don't fill the hole but just a touch to harden the plastic. I use a toothpick

Lift the upper shell away and you will find a white 8 pin JST XH connector that connects the upper hull functions to the controller unit.
Gently but firmly detach this connector.
The upper and lower hulls should be separated now.
and thus we end lesson #1
(pics tomorrow)
B