A lot of us, me included, have a problem saying no. Some say it is cultural but after too many nights watching too many episodes of Oprah, the fear of saying no is not just a Filipino thing. I am sure that there are a million different reasons why we just can't say no. Some are scared to say no because they don't want to reject another person. We all have been rejected one time or another and we know how that feels, hence, we avoid saying no. We are scared of saying no because we don't want to offend.
However, saying yes or maybe when we really mean no in the long run is actually worse than saying no outright. When we withhold our no we lead on that other person to that non-existent glimmer of hope only to get heartbroken when the time that yes is most needed. I think not saying no is actually a sadistic way of hurting a person. If at all the pain of rejection is eminent due to the NO, at least it is easier to recover knowing that one was not disrespected with a lie.
Of course, we still need to know how to say no in the most humane way. We need to make sure that our no is just a no and not a rejection of the person himself or herself. But more than being nice, I think a dash of sincerity should always be of paramount consideration. After all, a man is only as good as his word. If you give your word, keep it, or else, say no.
"I'd rather get hurt with your truth than be deceived with your lies." - anonymous (or I think from a song that I can't remember now)