Following the findings of positive psychologists 50% of the variance in the happiness of a population is determined by the genetic setup. Only 10% are determined by life circumstances.
40% is in your hands.
However, the first secret for all you scientific happiness searchers out there is to accept this ratio.
Then let's start working on that:
Don't expect too much from the circumstances but marry, have children, do a fulfilling job and try to stay healthy and the 10% are yours: no kidding
Let's tackle the 40.
Sleep regularly, do exercise and try to achieve something in your job or studies.
That's the baseline.
Then devote time to your friends and relatives, express gratitude frequently, be helpful, be optimistic about the future, live in the present moment, commit yourself to lifelong goals, and take setbacks easy.
So you can tune your happiness.
The other 50% we will leave aside for the moment, because that gets us into the realms of synthetic biology phantasms and eugenics.
Having said all of this (and I think that giving it a try is an excellent endeavor) my personal only true suggestion is:
Come as you are