Legends Guide.

General Basic Tips:
->Only select legends with ability 27 and above.
->Do not recruit more than three legends initially.
->The the legends you have initially should be 1 warrior, 1 monk and 1 seer/warrior.
->Dont be hasty in recruiting, first complete the legends task which gives you a "lark", a legend with 30 ability.

->For warriors: Maximize their courage, this should preferably your main legend, level him up and assign all archers to him, use him to invade wildlands.

->For seers: Maximize their strategy, if he is your main legend fill with archers and invade wildlands, if he is an extra then train him initially to a certain level and he can be used like your main and he excels at defence.

->For monks: My advice, Monks belong in your city as governor, there is a reason why they are called monks and not warriors.

Do not recruit many low level legends(level 20 and below) initially even if they have very high ability because too many legends are hard to train and they consume gold by the hour.

Later in game you will get high level (40+) and high ability legends so be patient.

Alternative(Fastest way):
You can also do what i did.
Do this if you want to invade lots of people and gather resources fast, then train large army fast.
WARNING: If you are doing this You must have a huge food production (like 20k /hr later in the game.)

->Get 3 legends (either recruit or take as prisoner from wildland) they should be warrior/seer.
->All should be level 15+
->Maximize the strategy of every one of them.
->Assign 2.5k+ halberds to each of them.
->Now invade people like crazy.
->If you invade a person with decent reputation you will carry back 150k+ of each resource.
(I loot 250k of each resource per invasion).

Special Advice:

After Experimenting a lot i have come to the following conclusion:

Early Game Legends should have a mix of stats between strt and crg , people differ over this, but now i am sure of this.