Count all valence electrons, adjust for charge, connect atoms, distribute remaining electrons and check the total. Typical main-group structures aim for octets with hydrogen limited to two; exceptions must be handled explicitly.

The model has a domain of validity. Explain its assumptions before using it in a changed context, then compare your prediction with evidence.

• A Lewis structure accounts for valence electrons as bonding pairs and lone pairs. It is a bookkeeping model before it is a shape.
• Do not silently create electrons to fill octets. The total electron budget must balance.