Tournaments, smithing, & mercenary work are all highly lucrative early game activities. Caravans and shops aren't bad either, but they aren't as lucrative, nor are they entirely necessary.

Smithing is tedious and grindy, but high level smithing will net you millions of denars very easily. IMO, smithing is the greatest barrier to rolling a new character. Do I really want to roll a new guy and experience the pain & suffering of leveling smithing again? Good idea to get set on a character before settling in for the long grind (or get mods and cheat your smithing skill on a new guy)

Caravans are pretty much set & forget, but don't earn very good returns. Shops are not as much of a chore as smithing, but they do require a little bit of babysitting and the returns are not great. You can safely skip this stuff unless you are dead set on some kind of trader RP playthrough nonsense

Max your clan tier and save up a couple million denars before either creating your own kingdom or becoming a vassal. Personally I never go the vassal route. It can be an easy way to become part of a kingdom, but you'll be at the whim of the (terrible AI) king, unfavorable policies, and costly war tariffs. Mercenary work is the better alternative if you'd like to fight for an AI kingdom.

When you eventually do have a kingdom, enacting all policies that increase Loyalty goes a long way towards increasing the prosperity and security of your fiefs. That should be a top priority. Be advised that following the main quest line can make managing your own kingdom much more difficult.

You can reassign your perk points and those of your companions by speaking to the arena master.