This process has been documented admirably elsewhere so many times, it's probably pointless me doing it again. The process is actually not that difficult to do to be honest, but just some very important points to note…
1. Be methodical. Photograph and document EVERYTHING! Even if you think, 'nah, I'll remember how that goes back', document it and the order in which you removed each piece. The chances of you remembering exactly which way that bolt came off in however many months' time is almost zero unless you have a photographic memory. I took over 1000 photographs showing pretty much every nut, bolt, screw, panel and connection on the car and I still reckon I probably missed some stuff.
2. Before you remove each part, ask yourself:
What is it called? What does it do? How does it do it?
It'll make life a lot easier later when you're trying to buy parts for replacement or repair/restoration if you know what it is that you're talking about.
3. Write a label for every part with a description of what it is and put this INSIDE a clear plastic zip-lock bag with the part itself. It's amazing how filthy this job gets, and there were at least a few occasions where labels fell of bags, and got so covered in grease and muck that I could hardly read them. Have loads of storage boxes and space in which to store everything that you are taking off. Try and organise the parts into logical boxes, e.g. interior, engine, ancillaries, external etc. as it'll make it easier for reassembly. I actually rented some local storage as it was just impossible working around everything that I had taken off, even in a large double garage such as mine.
4. Keep EVERYTHING! At this stage, you have no idea what is, or isn't available currently, and I've found some of the original stuff is much better quality than the 'new' stuff and it would be preferable to restore the original rather than buy new.
5. When the engine comes out, leave it attached to the gearbox and take it out in one piece and definitely enlist the help of a friend, it's a lot easier that way. If you're doing a full nut and bolt rebuild and the tub is coming off anyhow, then don't bother doing what I did and take the engine out with the tub in place. Having said this, when I did take the engine out, this wasn't going to be a tub-off rebuild!
6. Finally, take your time… this is going to be a labour of love, if you think you'll be done in a few months, think again!! If you're getting frustrated with something, leave it and come back to it another day, there will always be 'another day'.
I don't want people to think I'm trying to teach them to suck eggs, but as someone who has never done this before, the above were just few things that I found useful when I did the exercise.