i always find wessex a good start in 769, 4 counties, no vassals and several small counts around you to take and with larger opponents for challenges.
Are you able to take those counts without fabricating claims? Kent starts with two one-province-minors who can be claimed without having to fabricate a claim. Just borrow money, hire mercenaries, use the mercenaries to win one war, let the mercenaries go, wait for the levies in your first conquest to recover, and win the war with the approximately 2-1 troop advantage. (You can technically win both wars using mercenaries in one go, but it's more expensive, and you'll have to wait for a claim fabrication in any case.)
When you start, see if you can find someone with high diplomacy who will come to your realm, and use him as your chancellor. Once you have a large enough realm, you should always have someone with sufficiently high diplomacy, and eventually the "Chancellor" position will be more of a formality you can give to a powerful vassal. (Once you hit a certain size, you won't have to create false documents to fight wars for territory.)
(My Marshal position is also a formality. I can use commanders who have good military skill to command my armies, and give the Marshal position to a powerful, but useless vassal. The only position I won't compromise on is Spymaster. That always goes to the best intrigue score, no exceptions.)
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