[Endoperez]

Basically, a pretender that can take one province/turn from turn 3 or 4 forwards, preferably without any troops support. That will basically double your expansion rate.

Very high-power bless is another option, but it depends on a nation. Strategically fast (mapmove at least 2), resource-cheap sacred units are more useful than slow, resource-intensive sacreds, and having multiple attacks will double Water 9 or Fire 9 bless effectiveness, and quadruple Water 9/Fire 9 bless effectiveness. MA/LA Vanheim's mounted Vanir with F9W9 bless are perhaps the most common example.

Learning to expand well with national units is also important. Most expensive unit isn't necessarily the best, because numbers matter, and "missile units scale better than melee units". The latter means that even though X number of melee and missile units are both unable to conquer a spesific province, 2*X missile units can conquer it, but 2*X melee units can't. This works especially well with nations like MA Marignon, who can boost their crossbows with Flaming Arrows in middle-game.