Calicea,
I to almost always play a non agressive game. I usually play epic or standard length on King level. I prefer HUGE maps + 22 civs + 12 city states with more land and less water with raging barbarians.
My advice:
Think
small powerful / experienced army. I suggest developing the Honor policies first. Don't waste experienced units, withdraw them rather than lose them.
Use raging barbarians to maximize the experience level of your units. Throw in Honor and you get added culture and an added combat advantage (25%) for each kill.
I build two scouts to search the map and usually both end up promoted with in the first 50 turns. These units I keep for the duration....and continue to upgrade them.
The idea of a small powerfull / peaceful army is to have as much expierence as possible and upgrade. SO...create your small upgradable army with mele units, unique units, and arty units. I build archers only on occasion and make them expendable because once your in the industrial age there range promotions are usless when upgraded to riflemen.
Build good defences and place a fort or two in key locations where attacks are likely to come. Since your army is smaller that most AI's they will attack you. This is a good thing as it affords the opertunity for more unit promotions.
CAUTION - If you get carried away with destroying an AI who has DOWd you,
dont over extend yourself because you can and will attacked by another AI and then you will be crying the blues