will it improve just by working or is there a place where they give classes?
yes
> is there a place where they give classes?
dance studio on barb street, but it's not free
> And is it worth learning at school?
all game's most important perks are tied to your school grades, so it's pretty much mandatory if you don't wanna have a bad time bad time
> Any recommendations for jobs in the early game?
ask for jobs on domus and danube, new housekeeping content is there somewhere. get good at swimming and raid lake ruins (there's a group of students going to the lake after school you can join on sunny days for safe passage, good history knowledge will make it easier to travel there on your own). do be wary of the ivory necklace, it's easy to get and it sells for 2k which is all the money you can need in the first month, but there might be consequences. golden chastity belt has a 1% chance to spawn in one of the pots (among other loot), and it sells for the same 2k at the school museum (open on weekends), but you might accidentally put it on and there's no key (you'll still get the museum money for it though, so if you're into protecting your virginity - you might get the double value out of it). searching pots also raises your skulduggery skill sometimes, without giving any crime. if you don't mind crime, raid school lockers, then houses on domus, then danube, then connudatus, i think that's the progression. landry at the bar can help you launder your crime money. don't be too afraid of missing a payment or two early on, especially if you have bestiality disabled or wanna escape the civilization and it's problems for some time