Have wood coming in quickly and your rationing must be put to double. Set your taxes to "High" or "Higher". Have lots of weapon makers (for example, the blacksmith, pole turner...). With a lot of wood and gold you can get weapons quickly without buying them and losing gold.
-When starting a scenario you are required to build a stockpile with no cost. After building the required granary you can delete the stockpile for gold, then build another one for free. Repeat this for quick money. You can use this trick to get your buildings up early. Just use the trick, set up a market, and just buy raw materials needed to purchase buildings and units. Note: Materials in the stockpile disappear if you delete the building. Take advantage of pausing the game. Defenses and units will be waiting long before the enemy has a chance to blink.
-After placing your stockpile and your granary, just delete the stockpile to get gold. Put another one down for free. Keep doing this. You will eventually need to put raw materials in the stockpile, but will gain gold quickly.
-Once you start the game, build a stockpile and a granary in an open field. Then, keep building apple orchards, dairy farms, chicken farms, etc. When you have at least 40 months of food, turn your ration to double then raise the tax. Next, build a woodcutting camp or buy some woods. After that, build as many stone quarries and iron mines as desired. Sell all those resources. Eventually you will get more than 10,000 gold.
As Arthur and you are playing on the dragon island, put a siege camp in your castle and make two Enchanted Orbs. Put them on the bridge and have them attack the end of the bridge. Any enemy running across the bridge will get killed. Be careful because this also kill your units. If needed, have it to stop then run your army across.
Battle through Saxon Warlords to reach Sir Bedievere. Once you get him back to your castle, protect it. The Saxon Warlords have hired Pictish Boat Warriors to assault your castle, which will arrive from the sea. While doing this, you have to wait for Merlin to return from Ireland. Then, with the aid of Sir Bedievere and Merlin, destroy the Saxon stronghold around the Stone Circle. Afterwards you must build Camelot while under attack from Saxons. You must complete it before Lady Guenivere arrives.