I usually do the following:

1. Don't DoW anyone unless they DoW you first or unless they are a clear and imminent danger. (i.e 4 stacks camping all around your capital causing 1000 florins devastation)

2. Concentrate on building a perfect military, perfect economy, capable of meeting any task you require.

3. Agree to all ceasfires on fair terms (usually they are unfair even if you are much more powerful).

4. Donate all cash in excess of 20000, every turn. Usually I pick one faction and make them rich then the next. Í've produced a Frankenstein out of Sicily this way. But it is much better because at least then you see cool Norman Knights etc, otherwise you'd be seeing 15 catapults and 5 peasants.

etc....