Okay, a bit of early game advice:
- Where you start is irrelevant as you'll get a rendition of the same quest. Just be aware that certain choices during character creation may set you at odds with a faction. Find out which and make amends. It usually takes less than 1000 denars.
- Do the training field, it's easy experience
- Give the arena a go, it's hard but you have nothing to lose
- If you don't have them already, get a lance and a fast horse and start couching away, but....
- always check the enemy troop composition. Even pesky bandits have the occasional rouge knight, which will most certainly kill you and anything you could assemble at this point
- Outlaws, Bandits or Brigands are fair game, Vanskerry and Mystmountain not so much though not impossible
- try to get your companions together asap, maybe check the wiki and build your group accordingly. Some are expensive though.
- If you're not doing it yourself, make one low level companion a medic, another one a pathfinder, a third one a looter and a fourth one a trader (this is sort of a must)
Doing it yourself will yield a leader bonus of up to +4 either to your skill directly or to the respective companion skill if higher, for all partyskills.
- don't recruit everything you see, mobility is highly important. Check the steppes, you'll know what I mean.
- take prisoners (a lot) and sell them for profit. Certain weapons like the blunt tip lance will aid you in your quest. The skill doesn't hurt either.
- recruit prisoners. Sell anything you don't need but try recruiting the good stuff. If you're having trouble figuring out what's good, look at the sell value of the troops and compare.
You need some Persuasion for this to work on a reliable basis. Also some might escape at the break of night. If there are elite troops present which can't be recruited it will say so
on the screen
- check the prisoner stack of enemy groups as you'll be able to recruit non-elite units from that if you win the battle. You can also join massive battles and pick at least one troop
of every stack at the end of battle.
- both things deimoss said. The young xxx noble troop tree will come to an epic conclusion if you focus on the adventure aspect. Being a merc will pay your whole army's salary if you
have leadership 5 or better. To become a merc, talk to a lord of any faction that is at war. Just be aware that after this, you'll be at war with them too.
As for best troops, I'm afraid there is no such thing. There are some troops that have an advantage in certain aspects of the game, but you'll figure that out yourself.
For me it's more of a playing style question, so to each his/her own. My preference in the early game is to focus heavily on the mounted part, which will give you an "army" that does quite well against unmounted units i.e. the stuff you should be fighting in the beginning.