Wind the film somewhat slowly all in all. The gears are known to strip out.
Use a lens hood. Every time.
Flock the interior for contrast increase.
Mark Hama in Georgia is the best US guy for repairs. Essex Camera in NJ is another good place.
Jon Goodman sells light seal replacement kits for these cameras. Great material, great kits, great guy.
DO NOT do anything with the self-timer if the flash sync is set to M. NOT A THING!!! Seriously, the number one way to trash the shutter mechanism (assuming the 124G has an M setting).