Read the startup guide from the pros:
http://forum.crownofconquest.com/index.php?topic=871.0So that you don't waste points upgrading useless things and end up with sub-optimal characters. The first post is more about game mechanics and maxing out your turn usage, but you can get a handle on that now or later. The second post is about what to put your points in. And this is important as you can't change your character's skills later (you can make more characters though). Each skill maxxes out at level 10, so 1 character can have 2 x level 10 skills and 1 level 4 skill by the level cap of level 25.
I max out each classes main attribute and CON at 18, and put the rest into Agility. (or DIV for the luck bonus for Archers who already max out agility). You generally want to upgrade CON exclusively for several levels, the guide says once CON hits 40 switch to maxxing out each classes main attribute.
The guide focuses on building optimized combat characters, but you can use the same principles to build support characters. e.g. construction skill reduces time to make fortifications, and fletching skill makes arrows or bolts. Fletching uses Intelligence as the main skill, so you can train up a support mage (Do this after you've trained up your main 8 combat guys) with level 10 construction, level 10 fletching, level 4 metallurgy (which automatically repairs the mages equipment) and Max INT at every level (they will end up with 90 Int). You put them in a garrison armed with a crossbow, and they will automatically churn out crossbow bolts like a factory. You can add them to the party now and then, when you need their construction abilities, or when you want to get them to scribe scrolls of their daily spells (save these for the expensive ones, like the 10 point spell that blows up enemy walls), so that your main mage (who won't have 90 int because he has upgraded CON instead) can cast way more attack spells than he should normally be able to.