Plantar fasciitis is a degenerative (not inflammatory) condition. Studies using radioactive tracers have shown that the rate of tissue replacement in connective tissues is often extremely slow, maybe even zero. Therefore these injuries can be extremely slow to heal, and in some cases the microscopic damage is simply permanent.
Although people usually feel PF as heel pain, the damage is actually in the webbing that makes up the arch of the foot, which only happens to have a point of attachment at the heel. You just don't have nerve endings in the main body of the plantar fascia. Therefore the issue isn't really heel strikes or lack of padding in the heels of your shoes.
A study by Sullivan looked at factors that correlate with PF. Some factors that were not strongly correlated with PF were hours spent exercising or hours spent standing at work. This suggests that PF is not really an over-use injury per se. This is a common finding with many running injuries. Often they don't correlate at all with how much or how far you run.
The strongest correlations Sullivan found were with body mass index and strength of certain muscles in the ankle. Many other workers have found a correlation with obesity. Since this is a very consistent finding, and the question is how to prevent PF, the most solid answer is to make sure your weight is under control.
There are many treatments that have been promoted for PF, but the scientific evidence for almost all of them is weak. There is no super strong evidence of better long-term outcomes from massage, stretching, taping, therapeutic ultrasound, or modifying the patient's stride. A 2015 literature review by Landorf is mostly negative as to the results of treatment, especially in the long term for people whose PF doesn't resolve itself fairly quickly (as it does for most people).
There is pretty decent evidence, from a randomized but not blinded study, that chronic PF responds somewhat over the course of 8 weeks to the following stretching exercise. Sit with the ankle on the other knee. Use one hand to stretch your toes up toward your shin. Use the other hand to verify that the plantar fascia are being stretched, and lightly massage them. Do 10 reps of 10 seconds each per set. Do this once before getting out of bed in the morning, and two more times over the course of the day. There is no evidence that this helps over longer time scales. It has zero cost and is easy to adhere to, so it probably makes sense to try it.
Orthotics are the one treatment that is reasonably well supported by research. Custom orthotics are no better than cheap off-the-shelf ones. The idea that they correct problems with mechanical alignment is empirically false. Many podiatrists believe that choosing the right orthotic is important, and that they know how to do it; evidence doesn't support this. Orthotics provide an improvement in function that lasts for a few months. They do not give any statistically significant reduction of pain. After 12 months, they're no better than a sham treatment consisting of an orthotic made of soft, thin foam.
Injury Series: Plantar fasciitis in runners as a degenerative overuse injury
Treat Me, but No Tricks Please
Close Look at Orthotics Raises a Welter of Doubts
Effect of Shoe Inserts on Kinematics, Center of Pressure, and Leg Joint Moments during Running
Digiovanni, 2003, Tissue-specific plantar fascia-stretching exercise enhances outcomes in patients with chronic heel pain. A prospective, randomized study
Sullivan, 2015, Musculoskeletal and Activity-Related Factors Associated With Plantar Heel Pain
Landorf, 2015, Plantar heel pain and plantar fasciitis