
Some of my thoughts;
Fix your Empire > Raid with numbers
I found that fixing your empire first for the first fifty or so turns, then just unleashing great stacks of doom of Berserkers and a few Trebuchets is the way to go (e.g. 30-40 units per stack). The 52,500

target (Monarch) is achievable. I found it required ransoming a large portion of the map (close to 40 cities), some pillaging, and the slider turned up.
For starters; swap to Organised Religion, build Forges before Barracks and other city improvements, emphasise

, hook up the Deer, Fur, and the Clams, and start improving the landscape (e.g. cottages, farms, workshops, mines). If playing on a medium or advanced level, be mindful of too much chopping, as

can be a problem. Use the whip to get your buildings up quickly, although Granaries are not 'that' important as you have no

gain and will hit the maximum city size pretty quickly (where you turn off emphasise

!).
Technology-wise, Compass, Currency, and improved-civic technologies are priorities. Many tech's in this game don't seem to do that much, so work out what you want, and chase them at 100%, and then stop researching and pump out

. I see little point in chasing the 'Treasure' technologies. After getting your city buildings constructed, don't forget to switch to Theocracy. Mercantilism will allow for Specialist Merchants which will lead to the popping of some Great Merchants.
Early game easy pickings
Use your existing units to head straight south to continental Europe and take as much of that area as possible from West Francia - ransom captured cities such as Bremen and Medemblik and pillage the Towns. Either/Both of East or West Francia will develop metal-based Medieval units, so do as much damage as you can there early on. Ideally you'll get a unit to Level Four for the Legendary Saga.
Britain
The yellow tribe in central Britain; the Mercia, also can be pretty tough (swarms of Horse Archers), and taking their inland cities can see your SoDs go through a lot of punishment. Once you deal with Scotland, make sure to pick up your troops (don't have them linger there without a purpose) and head to Ireland to join up with any other troops since constructed. You should be able to ransom all of Ireland by the latter parts of the game.
Great Generals - first three in your capital
Your capital; Bergen, makes a great unit pump, so focus your first Great Generals there with a Military Academy and at least two Military Instructors so your Berserkers get three promotions such as; Combat I, Combat II, and Formation (if you're still dealing with Horse Archers). Longbows can get Guerrilla I, II, and III. King's Saga and Legendary Saga go in the Bergen too.
Navy
Be wary of Triremes - keep your Longboats in the ocean until you are in position to strike a coastal city. It may be worthwhile building two Longboats with Combat promotion(s) to protect the other Longboats in your naval stack.
One Sitting
I found that saving my game for later play ended up messing up the game as the computer didn't recognise my previously ransomed cities. Maybe it was just the way I did it, but I needed to go back and play a new game from start to finish without closing it down to ensure that the scenario played as it should.