Merchants

[Daveybaby]

First of all, as has already been stated, work on getting your merchants guild - build all of your merchants from the same city, and refuse all guilds except a merchants guild there.

The most important thing to do with your merchants (as with most other strategic units) is to train them up.

Stage 1 : Early Training
Initially you need to sit them on a secure local resource (by secure i mean: protected from the AI's merchants coming in and taking out your merchants through acquisition). To do this you need to either:
(1) Find a safe resource away from the action (e.g. as england most of the resources on the british isles should be safe)
(2) Protect your low skill level merchants with your high skill merchants, by aquiring any AI merchants as soon as they wander into your lands
(3) Move your low level merchants off of a resource if they are in danger of being acquired by a higher level AI merchant - enemy merchants will only 'attack' yours while they are actually trading. This is a bit of an exploit as you can take out the AI's merchants at any time.
(4) Use the 'fort exploit', and build a fort on a resource and put all of your merchants in there. This is a totally cheesy exploit but thats up to you and your consicence.

Keep your merchants trading locally until they reach level 4 - the value of the resource isnt really important - whats important is that over time your merchants will gain skills from trading.

Stage 2 - Aquisition Training
Then you need to move on to phase 2 of your training - acquisition. Move your merchants to the borders of your lands and start taking out AI merchants. Initially try to find a couple of low level (0 or 1 skill) merchants to aquire as this should be a dead-cert success, but in general only ever tackle a merchant with at least 2 skill levels less than your own, and you should be fairly safe. You will find that pretty much every successful aquisition will give your merchant another skill increase. Plus, you get quite a bit of money from doing this.

If a high level AI merchant wanders into your territory dont try to take them out - just avoid them like the plague. Sometimes they will go away, and sometimes they will just settle on a resource and then never move again until they die - but sometimes they will actively prey on your own lower level merchants, so keep them out of harms way.

Stage 3 - Profit!
Once your merchants get to skill level 7 or 8 its time to move them to somewhere really profitable, such as the aforementioned gold, silver, amber, spices, silk and ivory. Check this thread for lists of reource locations and their relative values.

Note that:
(1) The higher the skill level of your merchant, the more the resource will be worth
(2) The further away a resource is from your capital, the more it will be worth
(3) If you have trade agreements with the faction that owns the land the resource is on, you will get more money
(4) If a region has multiple copies of the same resource, then controlling them all will gain you a monopoly bonus - e.g. i like to send 4 high level merchants down to constantinople and nicaea and monopolise the 4 silk resources down there.

By this stage your merchants should be of a high enough level that they are virtually immune from takeover by AI merchants, so you can just leave them where they are and let the money roll in. However, in some congested areas (e.g. constantinople), merchants can get barged off of a resource by a passing diplomat or army, so make sure to check on them every now and then to make sure they are still sitting on their resource properly.

Eventually your highly skilled merchants sitting on valuable resources on the other side of the map will die of old age. I always have a production line of merchants going through the training process so there are always suitably skilled merchants ready to replace them. Once you get a higher level merchants guild and the higher level trade buildings, you can train merchants who will start out at skill level 4, which will save quite a bit of time and effort.