Well I'm certainly no expert spray painting!
The spray gun is a Binks Bullows '230' which I have had for probably over 30 years - as you can see it's sprayed a few colours in it's life. My 'method' of cleaning is:
a/ Pour out any remaining diluted paint - (I save it in a clean sealed plastic milk bottle if I have more to do later )
b/ Wipe out the reservoir, nozzle face, dip pipe etc with workshop tissue
c/ Put in about 50 ccs of thinners, shake it around, and spray into a wad of tissue - discard remnant
d/ Repeat c/ above
e/ Again put 50 ccs in the reservoir, swill it around then leave it in the gun
This seems to keep the workings clean and not clog up ensuring it's ready for next time