1. Blink your eyes less often. Though most of the times it is unplanned, uncontrollable, involuntary and painless, it can still be done. Try.
2. Bite those lips, upper or bottom or both as long as you can still let some air through it but never, breathe through your nose for it has probably by then, be blocked.
3. Inhale long deep breath through that tiny air passage, and hold it, for as long as it lets you live.
4. And please, keep those facial muscles as straight as your wrinkles, as if you're lifeless.
5. Do anything, everything you can...
...to not cry.