My free answer is: Be natural. That in itself is admirable enough. How I see it is treat others the way we want to be treated. Honestly welcome people who are different. It makes life RICH. =D
One thing that's always crossed my mind about books like these are:
1. It's another profitable gimmick. Tell people they aren't good enough. Make them feel like crap. Let them know what their flaws are. Then the author has x,y,z answers to market their solution. It may work short-term, not sure about long-term. [con+/--]
2. The advice may help for some, those who really need it. If it's successful, then great! [pro+]
Live & let live. If we learn to accept people for who they truly are, then it becomes a collaborative unconsciousness where people will want to work in harmony/unison with one another, at the same, bring out the 'Best' qualities within themselves. I think for those who are really popular, it's usually because they don't have to 'try' hard to achieve it. That's just who they are. For a book to tell people ways in which to behave- to me, is unnatural, inauthentic. We all have positive qualities within ourselves. Recognize. Rejoice it!
So what if someone likes to be a bit more introverted? Respect that. So what if they're not all warm/cuddly? That's who they are! For those who are into the superficiality of having shallow friendships, so what? Just don't expect everyone else to be the same.
My observation is: The more 'fake' or forcibly positive a person tries to be, the more unnatural he/she is, the less likable they will be. It's all in the vibes they give off. If they can't be true to themselves, who can be true to them? So, the author may as well publish several other sequels, because the real answer is: There are no absolute rules. If there are things that prevent oneself to be happy- Work on goals to achieve it, which should always stem from within, not without (the externals don't bring happiness, trust me). Enjoy life. Go with the flow. Laugh. Things will naturally work out for the best when we learn to be more genuinely understanding and humane to ourselves and to others.
I tend to see things the Rogerian way. Treat people with unconditional positive regard. At heart, people just want validation for who they are. Little acts of kindness we share to people in general, including those who are a bit socially different, outcasted/or depressed, the more they will naturally want to be more sociable, happy. It's all in how we treat others in our daily lives. Every action has it's own consequences. Make it a good one! If someone's rude or crosses over our personal boundaries when all we've done was show them 'R'espect, then don't give them the time of day. It's their LOSS. It's about standing up for oneself when the situation calls for it. I hope that's not too much ta ask for? (Sorry so long- I wish I coulda shortened it.. Tehe). Great topic!