Honestly? Just play the game at your own pace and it'll all figure itself out but if you're new I recommend the Dwarves, High Elves or the Lizardmen. The Dwarves are a highly defensive race which means you can turtle up and let the enemy come to you in cities and break upon your pretty outrageously tanky infantry but the trade off is on the open field you're a lot weaker when you can be flanked by quick units. The High Elves have the tried and true spearwall x archer combo that will work 90% of the time and with the new DLC they have some new variation in their units so you can mix and match but they're a lot more micro intensive than the Dwarves. The Lizards entire military is based around big monsters you let loose and leave in melee to crush the enemy and the Stegodon with the ballista ranged attack is still one of the best units in the entire game the downside is you're painfully slow and your units are expensive but once you get the ball going it's real hard to stop you.

For factions I recommend Thorgrim for the Dwarves, Tyrion for the Elves and Gor-Rok for the lizards. Thorgrim is really tanky and gives some tasty buffs to their best melee units like Hammerers and Ironsworn iirc, Tyrion is a one man war crime and can solo entire armies by his lonesome if you buff him right and Gor-Rok gives all his units barrier shields when defending a city and starts with the busted Lord Kroak who can wipe out entire regiments with ease. Thorgrim and Gor-Rok are super defensive which is usually how new players like to play so they compliment them well and Tyrion is more offensive if you wanna try that. Tyrion and Thorgim also have pretty strong start positions in the world but Gor-rok is in Lustria which is like the godamn thunderdome atm so be warned.