Get everything spinning (whirlpool like) before you turn it upside down to dump it, and then keep it spinning (don't go crazy) once you've got it in the gold collection bottle you're dumping it into, and any fine gold will usually get spun out that's hung up on the sides or elsewhere.
Always, always do it over a gold pan or large bowl (like Fullpan says). All kinds of crazy things can and will happen from time to time, and more than once I've been very happy I was pouring my gold into bottles over a gold pan.
Of course, if all you do is pan out nuggets and pickers, then you won't need to worry about spinning the sucker/sniffer/snifter/snuffer bottles (man, there's a lot of names for the exact same thing, isn't there?!), as those chunky pieces will usually slide right out with the gravity's assistance only.
All the best,
Lanny