A couple of hints, if this is your first one :
Before you unscrew anything mark it so that you can screw it back to the same position.
Make notes or take pictures of what you are undoing so you can put it back together again.
The front bezel comes off using a sink stopper or any other round object wrapped up in a thin rubber glove.
For JIS screws get the proper driver or use a small flat blade - normal crosshead will chew up the slots.
Watch out for the aperture ring detent ball bearing - it will be held on with grease but will invariably drop off later.
Borrow some cold cream from a female friend - this really works to remove fungus.
As you take it to bits lay out the parts logically, with any glass stick a bit of tape on one side so that you put it back together the right way up.
The glass coating is quite tough so don't worry too much about damaging it as you clean off any grime.
Wear thin disposable rubber gloves when you do the re-assembly.
The old lenses are easy to take to bits and clean - not so with the modern plastic bodied ones
Watch out, it is a form of LBA, before you know it you'll be compulsively searching eBay for 'Pentax lens with fungus' every day ...