This piece for Malachain collects the advice that holds up in practice.
Thunderstorms often build quickly in the afternoon, especially in mountains during summer. Check the forecast before setting out and plan to reach exposed ridges and summits early in the day. If you hear thunder, lightning is close enough to strike, so it is time to move towards lower ground and shelter. No place outdoors is completely safe during a storm.
Avoid isolated tall trees, open fields, hilltops and water, and keep away from metal fences. A building or an enclosed vehicle offers the best protection. If a group is caught in the open, spread out so that a single strike cannot injure everyone. Wait at least thirty minutes after the last thunder before continuing, because storms can return unexpectedly.
There is more to learn on this subject, and the linked website goes into greater depth. Treat this article as an introduction rather than the final word, and check any important decision against up-to-date, reliable sources before relying on it.
If you try any of these ideas, start small and adjust them to your own situation. What works for one person will not suit everyone, and it is fine to keep only the parts that help. Writing down what you changed, and what happened, makes it much easier to see after a few weeks whether the effort was worthwhile.
The most useful step is usually the first one. Pick a single suggestion, try it for a couple of weeks, and then decide whether it is worth keeping. Small, steady improvements last longer than ambitious plans that are hard to maintain once everyday life gets busy again.