Negotiation is neither an art nor a science.
No two negotiations are the same. However, if you are truly interested in the position, it is in the interest of both parties to explore the areas of flexibility, the areas where negotiations can produce an acceptable outcome for the overall compensation package. Being reasonable and empathetic with the other party will lead to satisfactory outcomes. Negotiate on all potential dimensions of the compensation package. Know your constraints and what is acceptable, and learn their constraints.