The electric field is defined as the force per unit charge exerted on a small positive test charge placed at that point. The rules for drawing electric field lines for any static configuration of charges are
The lines begin on positive charges and terminate on negative charges.
The number of lines drawn emerging from or terminating on a charge is proportional to the magnitude of the charge.
No two field-lines ever cross in a charge-free region. (Because the tangent to the field line represents the direction of the resultant force, only one line can be at every point.)
The line approaches the conducting surface perpendicularly.