[Gandalf Parker]

A) send out scout. maybe toward farmlands or chokepoint.
B) put mage/pretender on research,
C) put everyone else on patrol.
D) turn taxes to 200%
E) purchase mercenary (optional in MP)
F) purchase troops best chosen to fill needs in the troops you have + the mercs (if you still lack shooters or large flankers then get those)

Turn 2:
Move scout.
You should now see your neighboring provinces. Pick one you can win since the next one and the one after that will be getting reinforcements. Also consider if you are most in need of gold or resources in selecting which ones to attack first. You want to be able to continue straight around your capital so if there is a blocking mountain you should start one one side of the other of it so you can swing full circle around your capital without having to take a two-turn sidestep. But most important is one you can win.
Attack that choice, and turn taxes back to 100 so you wont kick up your unrest.

Purchase mercs, purchase another leader and troops.

Turn 3:
Move scout.
Set defense to at least 1 on that new province. Check recruitables to see if there is something extremely useful.

Have the first army move to the next capital-neighbor. The new army#2 should be able to attack that same province. You MIGHT try sending them to a different province but that tends to take VERY good understanding of all the battle formulas to take that chance.

At capital purchase mercs and new leader with troops

Turn 4:
you get the idea, repeat until all of the capital neighbors are taken. THEN you can pick a direction to expand in (maybe you found another nation by then?). You can consider buying scouts, or mages, instead of a leader each turn.

Personally, I avoid spreading like a big puddle. I prefer to take a line toward the other nation leaving indepts on both side of it. Its easier to defend. Later as I send out armies I will take out the side sections.