In terms of longevity now or very near
1. don't eat garbage and exercise
Some sites on longevity enhancing lifestyle that has more chance of longevity
2. There seems to be some promise with calorie restriction (but many people are unable to incorporate it into their lifestyles.). There is an alternate days of semi-fasting approach as well, which could be easier to adopt. There is work on drugs and gene therapy to achieve these effects without lifestyle modification
Calorie restriction linked to mitochondria one of the seven pillars of SENS
So it seems that SENS is an avenue worth pursuing even based on current and near term work and research.
3. Take the tests needed to detect cancer and heart disease early and then make the lifestyle changes or take the necessary medical interventions. Find out your own higher risks based on family history.
4. Look at modifying the environment (air polluition) and public health to reduce chronic disease
However, besides the near term steps for important small gains I also look at the high potential and underfunded opportunities. This is where a little more effort can bring a lot more rewards. So first two on the list are SENS and molecular manufacturing.
I also try to find overlooked ways to use old or near term technology and processes. An example is my proposal for devices to gather a lot more data minable medical data for research and for the development of personalized medicine.