The Three Fold Law

It depends on who you ask. If you ask a Wiccan, then yes. The three fold law is true. Whether is be good or bad energy you send out, it will return.

What are other branches of paganism?

There are so many. Get on Google and you'll be able to see :)

With the internet,you won't believe the nonsense you could see...

There are "3 Fold Laws" also "10 Fold" It all depends on your beliefs.

We are also taught early in our spiritual journey as Wiccans about the Three-Fold Law, that whatever we do for good or ill returns to us three-fold. . And again it becomes a concept rife with misunderstanding and misinterpretations. We behave because we are afraid of being smacked with the Karmic paddle. Being good little Witches because we fear punishment if we break the rules does not make ethical beings, just clever ones. There is no Karmic scorekeeper out there keeping a list of who's been naughty or nice. There is no Divine retribution, or something like the Christian Hell for violations on the Rede. What the Three-Fold Law is telling us is choices of action have consequences for which we alone are responsible. And if our choices are consistently negative or harmful towards others, then the energy which tends to return to us will also be negative and harmful. To live our lives full of anger, guilt, and negative thoughts can lead to both physical and mental illness right here in this lifetime. In effect, we become the tools of our own Karma. So, what kind of energy would you like to wake up and find on your doorstep one morning??

There are many, many different branches of modern Paganism. But some you might want to learn more about include:

Asatru

Canaanite Reconstructionism

Celtic Reconstructionism

Druidry

Heathenism

Hellenismos (Greek Reconstructionism)

Religio Romana (Roman Reconstructionism)

Kemetic (Egyptian Reconstructionism)

Slavic Reconstructionism

Sumerian Reconstructionism

Wicca

Witchcraft (religious form)

That should give you a good place to start learning about some of the branches of Paganism.

I found this post very insightful and helpful. Thank you.

Only when you do something really messed up, otherwise punishments are equal to the crime.

There is also something similar in Christian belief systems - namedly that giving alms (helping the poor, widows, orphans etc.) has favourable future impact. Here are some quotes from Ben Sira:
Store up almsgiving in your treasury, and it will rescue you from every disaster
Kindred (family) and helpers are for a time of trouble, but almsgiving rescues better than either.
I would hope that whatever one's beliefs are, people see the merit in helping those less fortunate. I do find it interesting though, this idea of only 'behaving' out of fear or cleverness - I think I prefer the idea that one can be ethical out of one's own free will. It's a more empowering idea. Certainly organized religion of any form brainwashing people into doing things out of fear or guilt is not something I smile upon. Anyway, I'm getting a little off-topic...