How to write ionic equation?

All ionic compounds and acids can be dissociated into ions in aqueous solution. For example,

NaCl(aq) → Na⁺(aq) + Cl^–(aq)
H₂SO₄(aq) → 2H⁺(aq) + SO₄^2-(aq)

How to write ionic equation? For example,

NaOH(aq) + HCl(aq) → NaCl(aq) + H₂O(l)

All compounds which can be dissociated should be separated firstly.

Na⁺(aq) + OH^–(aq) + H⁺(aq) + Cl^–(aq) → Na⁺(aq) + Cl^–(aq) + H₂O(l)

The same particles on both sides can be cancelled out to deduce a net ionic equation.

H⁺(aq) + OH^–(aq) → H₂O(l)

Based on the ionic equation above, how do you understand neutralisation is an exothermic process?