Weapons: there are so many fun ones that no matter what you choose, you'll want to try the others. But also committing to one tree pays off, so I'd reccommend switching on different playthroughs.
That said, I like runing bow>polearm>sword because they all have fun use, and spears felt harder to use at first (before I found the glorious [Coachable] tag and the holy X-key of Antioch).
Leadership and Tactics: it'll take a LOT of time to level these out of range of first couple of points. And tactics is currently... of iffy use unless you're incapacitated, but that's because before 1.2 it was arguably too strong. Assign Quartermaster to yourself, and you'll raise Leadership passively. Parties seem to be problematic to some atm, but after reaching higher clan rank, you can keep them on a short leash. Important to put points into eventually, but at least with my playstyle I get perks here waaaay before I have any use for them.
Smithing: if you're gonna go that route, put one - but I'd advise putting it waaaaay off into the build, because it's neigh useless before you can buy all the hardwood. You can make a lot of money or a little money in a pinch before that - but you'll have to stay static a lot. Can play nicely with ie infantry character or if you're otherwise injured a lot and need to stay in city anyway.
Trading: can't comment, because I always end up doing traders, and yet 1 point already seems too much, but then there's the town-buying thing. Whatever you do will be good - you can be efficient trader with 0-1 points in it, and it can win you the game if you manage to actually max it out.
Athletics - at least one. Probably needs a lot of points if you plan on doing infantry fighter, otherwise can be quickly trained in 1-group bandit camps.
Bow - so good. In 1.3 beta it seems it finally been nerfed and that skills affect spread - previously they hit centre of reticle (adjusted for distance) every friggin time.
Crossbow - wonderful weapon. For your vlandian recruits. Note that the perk allowing use of every x-bow is still inactive. Still want to play with it, but again - you can do so ie at siege first. Wouldn't reccommend if you gotta ask.
Charm - it'll be patched-in any day, currently very uneven. Doesn't affect quest conversations, but is a big deal with nobles and rep, when you get a monit you get X rep, you get a small bonus to it ie +2,24 and not +2. And since you lose rep for various war acts, it'll always be worth rebuilding in some contested areas for better resupply of recruits (with high rep you get access to higher seeds of recruits of that NPC + the'll give you fighters even if they are at war with your faction). Each time you siege a city for example: -5 rep. Same goes for raiding (even if you're just a part of an army - buy can leave and rejoin), and I suspect we don't get info when our companions do it, or there's other factors that'll lower your rep somewhere.