In addition to the many good techniques that have already been shared here:
My usual technique with the screws on Japanese carbs is to use care when unscrewing them for the first time, as they're generally stuck on there pretty good and it is easy to foul the heads.
I use a JIS screwdriver on them:
If the screws are particularly obstinate, I use some Grip Doctor I've had banging around the garage for years:
I've heard that valve lapping compound, or even Ajax or Comet abrasive cleaners work well, too.
If I did not damage the OEM carb screws on removal, I reuse them. When I put the screws back in, I always treat the threads with some
Anti-Seize. I make sure some of the Anti-Seize gets smeared underneath the screw head....something I never do for any other application. I never have any problems after that.
JM2CW!