I was getting close to making a similar post. I do all of these things.
Also, using that Organized + Adventurer trait with Sovereign -really- helps. If you got that route, be sure to buy every cloak, ring and mount you can to make your Sovereign and his/her entire party even faster!
Also, summoned monsters REALLY help. They're stronger and tougher than troops, have as much health as a stack of troops (but if they lose health, you don't permanently lose a troop -- just heal up in a city and they'll get fully restored!) and best of all cost no gold to maintain! They are really great escorts for all your exploring units. I generally get a stack of heroes I've recruited with the sovereign ... at my earliest convenience, I will Imbue the champions with the highest INT (so that, as they get experienced and have more mana, that strengthens their spells they cast). Its best to Imbue a recruited hero with a high INT right after recruiting them, that way you can up the new Hero-caster's mana at their first level-up. As soon as they have a mana pool of at least 5 so they can cast Summon Familiar and Teleport, I generally let them part from my sov's stack to do their own thing, cover more ground that way. When I start getting summoned critters costing 15 or more mana, I will let the 5-mana Familiars serve mostly as city guards as they get obsoleted by the higher level summoned critters.
Big kudos for this thread! This should be the basis for a beginner's tutorial guide.