E points along the tangent to the lines of force. If initial velocity is zero then due to electric force, charge particle, if positive, always moves in the direction of E and opposite to direction of E, if negative. But let's take a case where the initial velocity is not zero, i.e., let say charge particle is released with some velocity making an angle 90∘ with lines of force. Then in this case two velocities act on the particle as shown in figure (one due to electrostatic force and other the initial velocity). So, the net velocity will not be in the direction of E. Hence, charge will not travel along the electric lines of force.
