To appreciate others is to respect your-self.

Showing appreciation to others for their works and contribution, irrespect of how small the contribution is, is a respect to that others. In return, they will respect you and appreciate your kind words.

Imaging, one person doing something in his capacity of his job position and you do not think that he or she is doing it with the intention of benefit to anybody at all, and not withstanding, you thank him (or her) for the effort he / she made, would your appreciation change his attitude or behaviour in the future?

A kind word is like perfume; if you spray it on others, a couple of drops will stay on you

Beautiful words. Perfume spraying on others, you are actually getting your fragrance of the perfume. People love those words and people love you. So, get yourself a lot of perfume and don't be stingy. Spray and spread those kind, encouraging, motivating, positive, gentle and good perfume on people you meet.

A person who always makes excuses for himself can never improve

I think this short saying is very wise and true. This kind of people who always make excuses are the same people who put blames on other people when things have gone wrong but, when things are ok and are promising, they always claim they are "the one who did them, and because of us, things are rosy" and proclaim their credits.