1) Eat a good diet, and a good amount of said diet, neither too much nor too little.
2) Don't take in too much of things that are toxic in excess, e.g. alcohol, and be wary of dependency
3) Avoid altogether certain other addictive/toxic substances, e.g. tobacco (especially in the form of cigarettes), heroin or crystal meth.
4) Exercise. Regularly, in whatever way you find fun and is otherwise suited to your health (e.g. not likely to aggravate arthritis if you have it)
5) Stay active generally; especially after retirement or while unemployed.
6) Maintain a generally safe and healthy environment at home, at work, and while commuting
7) Take appropriate safety precautions, from sunscreen to condoms
8) Seek appropriate preventative measures, such as immunisation, cancer screening, dental check-ups etc.
9) Seek appropriate care and support both when you're acutely ill, and with managing any conditions you may have.
10) Seek a happy and fulfilling life.
Also, in interpreting and applying each of these, it's well worth remembering Bertrand Russell's first injunction: "Do not lie to yourself".
So... does this work, as a broad plan? How does the emphasis feel to you? In particular, is there anything major that you think I've left out?