Quests aren’t necessarily a strong point of Mount & Blade games, but there are more in Bannerlord than in the previous titles and they can yield some decent rewards. Aside from items, they also provide money averaging 400 - 800 denars. Most of the minor quests relate to trade schemes, either with honest merchants or criminal gangs. Honest merchants might ask you for a favour in the form of taking a certain amount of goods from one settlement to another for a share of the profits.
Alternatively, you can accept the quest and then steal the goods, selling all of them for a profit. This however will result in poor relations with merchants in the region, something which is much easier to lose than to regain. If you’re committed to the life of crime, you can take quests from gang members in any major city to transport goods illegally between gangs. This will upset local honest merchants to the point where it will prove incredibly difficult to win back their favour.