I may be being too simple, by Lewis structure I assume you mean Lewis Dot Structure.
Something helpful I was taught is that, let's say your dealing with Carbon a four valence electron element- place one dot at top, bottom, and each side. For other elements use more or less dots. The element to be bonded (Lewis dot style) use x es for its' valence. Dots usually are used for symbol for electrons available for bonding... I'm starting to trip over my words...I should just delete this, although there is a slim chance it may help, therefore I add it and see if a more experienced member can untangle my verbage.
I do know that this method is very helpful in determining if lone pairs are present.