I had a question about the way to earn bonus tokens. My brother managed to get to 20 power before getting his troops killed and conquered and he got 100 bonus tokens. I was wondering if there are other ways to earn bonus tokens and if the bonus tokens for 20 power is a one time thing or if it's for the first time you reach 20 power for the era?

it's a one time thing, first time u reach it.
you can also get some bonus tokens by clicking ufos (1-5 chance, and 5-10 tokens each time) or wrecs, who give x10 as many bonus tokens as the ufo's
you can also try joining the guide team, think tank, bug tester team or Public relations team
(to try to join those go into "user controll panel"->"user groups" then just try out the one u want
later there will be more ways to get bonus tokens =)

hole this helped

That helps a lot. Thanks for the time.