First of all you should be very well behaved as far as your personality is concerned toward that particular girl whom you want to make happy. Your personality should be very much presentable as far as your dress is concerned, your conversation and your normal behavior. Girls usually like those boys who take care of all the above-mentioned things.
Secondly you attitude towards that girl should be very positive and loving. You have to make that particular girl realize that you will take care of her every act and feelings.
Thirdly you should be very touchy in fulfilling her demands and needs. I hope if you act upon these simple formulas, you can make any girl of the world happy. If you think that these formulae which I have told you sbout are not enough, and the particular girl whom you want to make happy is a difficult one, the only thing is that you will have to work a bit harder and my formulae will surely make her happy.