I'm an Alfa newbie, so apologis if this appears elsewhere (i did search but couldn't find anything!).
Here was my 'process of elimination/correction' for the door squeaks/clicks/creaks/groans on a 147 3-door:
Clicking/Banging on each 'detent' of the check strap
- check the check strap bolts for tightness. Single 13 or 14mm bolt where strap is attached to body, 2 x 10mm nuts holding metal 'cups' to rubber dust seal/gaiter on door.
Creaking/squaking from front of door (leading edge, near front guard) or rear (near door latch mechanism)
- Check if door mirror bolts tight (3 x silver T35's from memory, one exposed and 2 others hiding under the black plastic triangle at leading edge of door), and check for dirt between rubber outer window seal and mirror.
If these are tight, check painted (not silver) T40's on door inner skin (front - just under rear view mirror bolts, rear - on trailing edge of door, just below bottom window weatherseal, above door catch mechanism) - make sure they are tight.
Clicking noise from 'B pillar' (central pillar) when taking off, slowing down, going around corners etc.
- Open door, Get your trusty can of Silicone Grease Spray, spray liberally on the catch mehanism (where it grab onto the locking pin on the B pillar). Then get a screwdriver or similar to 'close' the door latch whilst the door is open - spray again liberally with silicone grease spray (this took me a couple of applications to get 100% fixed as my car had a bit of red aussie dust in the locks to get rid of).
If none of the above solves your noises, then you may need to replace the check strap - costs about A$95 from the dealer.
Hope this helps.