So, if you ask me... I would go for this LAST tips >>>
ex: I was asked to wear contact lens for 'catch light', especially if it was potraiture.. Well, I buy those contact lens eventhough I don't wear glasses. It takes me half hour to put them on my first time and 5 mins on my second time. Eyes are the number one attraction of potraiture if you must know.. Even make up artist would spend more times on eyes rather than other things..
ex: Look up on Tyra Bank tips on how to smile with your eyes.. This is one helpful tips from professional that you can learn from..
I'm not a professional model who can give you excellent tips. Consider this LAST tips as your last choices of tips after those pro you ever known..
Hope this helps... \(^_^)/