i've recently relived the Settlers 2 experience. It's still one of the best games around.
I came here looking for tips. But i thought no one would mind if i dish off some..
1. Only build barracks to expand, halting gold coins from arriving each time. That way you save on sugar cubes (stones). However, you should have guardhouses instead on your borders...or better yet...
2. Build your castles on enemy/your territory borders. With maximum soldiers on the borders then you can take full advantage of your gold coins. If you notice each gold coin will upgrade any number between 1-4 soldiers and you can get the maximum in castles. You'll only need 12 gcs to fully upgrade 9 privates to generals in castles.
3. Do not cramp the front of your storehouse/hq. Create a spoke-like roadnet on it so that resources can easily be disseminated from it (and you can avoid the 8-resource problems that usually occurs in the mid-end game.
4. For coastal areas, build fisheries whose sole road exits lead to mines. The fish will immediately be taken into the mines and will not be lead back to your storehouses.
5. Always scout. You may be building that castle only to be burned by a catapult as soon as the first soldier moves in.
6. Clear out the initial area with woodcutters and a few sawmills. Do not build forestries yet. Later when you have a good area away from your HQ, build a Storehouse, then surround it with 3/4 sawmills, then 3/4 Forestries, then surround the circle with your woodcutters. This will serve as your lumber factory.
7. What actually lead me to this site is because I read somewhere ages ago that Pig-Farms/Slaughterhouses suck big time. I'm still trying to confirm this though I think this is correct since you can easily have a huge stockpile of bread while you may have meager denominations of meat. Also, Pig-Farms take a lot of space which I would rather have for Farms. Still, it doesn't feel right to deny your populace of the right to eat meat. hehe
8. A helpful method I use to remind myself that a mountain tile has been dried up is to put up a flag beside it that doesn't have any road attached. Once you've dried up an entire mountain you'll have a mountain full of flags - like what you would see on a middle-age battlefield sans the corpses.
9. It's not always good to have too much of a free thing. Don't get too much water since it's free anyway and producing too much of this will only clog your road network. Stop their production. This isn't true for wheat though. You never can get enough of wheat since they are easily manufactured into flour->bread.
10. Play with the transport priority system to get used to it. What I usually do during the early game is put food transport on top so that my mines don't stop...err...mining. This can also be used to stem off resource congestion when used in conjunction with building more roads.
11. Those donkeys are very important in the mid-end game when there are too many resources going around. Don't underestimate their use.
12. It may be wise to empty your HQ of resources so that these can be brought to a storehouse where they are closer to the intended user. Take note that if you do empty a specific resource, put that resource on top of the transport priority.
There are still a lot of features that if you screw up will paralyze your game. Just play around and address issues as they come. The default settings don't really help that much so you're better off experimenting your own.
I wish I can read other tips from other players. Info on Settlers 2 through Google is scarce.
Cheers!