As Mister_X mentioned, in the US, start with the National Speleological Society at https://caves.org/ There is also a sub-reddit at reddit.com/r/caving/ Definitely find a local group - if there are caves in your area, there are probably also cavers who explore them.

Basic safety rules include: cave with groups of 3 to 6 people, some of whom have experience, bring 3 independent sources of light, use helmets and headlamps, avoid hand-held lights (a strong sign of inexperience or incompetence), leave word of your plans - where you are going, expected return time, who to call for help - with a trustworthy friend. Some basic knowledge of geology is useful, as is comfort with physical contortion, sturdy clothing, and an ability to orient and visualize in 3-dimensions in environments that are far from rectilinear.

Respect the culture of secrecy about cave locations, which helps protect them from damage. Take nothing but pictures, leave nothing but footprints.

A proper club, who will give you training and supervision and carefully guide your initiation.

In Britain there are a number of good university clubs (I learned with ULSA at Leeds) as well as established local clubs like RRCPC, Northern Pennine Club, and Mendip Caving Group. In the US, the National Speleological Society has a network of local 'grottos'. There are established clubs in nearly all countries with good caves.

Also, caving with other enthusiasts is great fun. Outside of tech, the cavers were the closest I've ever found to 'my people'.

A few years of training with experienced people is enough to get you in situations where you would be killed by mistake on your own.

A decade should be good enough to keep you alive most of the time.

You have to learn it with a club. A good club is the safest option, they will teach you the techniques, the places and the safety. Although it's still dangerous and accident may happen even with the most cautious people, like for diving or climbing