I wrote this before on the FAQ page:
How do I train/raise my leadership? Recruit companions of sufficient difficulty. If you're having trouble meeting the leadership requirements to make the attempt, Craneharbor has initial leadership training available. You can also equip a vest or a tabard clothing item which contribute leadership points. A good first recruit option is the Page. He has leadership and will make recruiting other companions easier.
You can find the Page in the Visitor District of City of Hawkoria, in an Inn.