Any expereince portrat photograher will tell y'all if you have to ask folks to say "cheeses" to evoke an expression, you are in trouble!

Most rookie portrat shooters are busy learning all their lighting, exposure, ratios, and all that technical stuff that they leave their people skills behind.

Firstly, not every portrait needs to be smiling- nothing wrong with a whole gamut of expressions. When a subject force a smile they often look like a jack-o-lantern. Some folks never smile or don't want to be portrayed with a grin. A good conversation with folks will bring about pleasant and natural expressions.

Not everyone has the same sense of humor. What might be hilarious to one person may be distasteful to another.

Youg kids will react naturally to silliness- and I am good a that. Some adults will react well to silliness as well- if you catch them off guard. I have had several "executive" portraits sitting where the ad agency or art director wants a smile or at least a warm approachable expression- and the subject wants to come off as a "dictator". He sits there, with his arms folded, looking like Mussolini so in my last ditch effort to satisfy the powers that be, I'll balance my handy Kermit the Frog puppet or Oscar the Grouch puppet on my head- at that point, waht to I have to lose? If the subject questions my behavior I assure him that "they will bring me back to the institution after work"- that usually does the trick!