When drawing for example the Lewis structure of nitrate ion (NO3)^-1 whould it be wrong to draw nitrogen and oxygen separately and then try to figure out the structure of the ion? In that case does the nitrogen give one of its electrons to the oxygen? cause a nitrogen atom does have a lone pair of electons but in the nitrate ion they are gone.
Each Oxygen atom has 8 electrons surrounding it and so does Nitrogen. 2 electrons form a bond pair and hence a bond, thus they are no more a ‘lone pair available for donation.
In each N-O bond 2 electrons are used. The point is that nitrogen uses all its 8 surrounding electrons (which constitute an octet) in forming a total of 4 bonds, 3 single bonds and 1 double bond with Oxygen atoms.
So it has no electrons availed freely to become lone pairs, it thus has a formal positive charge on it and no lone pairs available for donation. Essentially what you did in a way, is absolutely correct, just the last reasoning you missed.
Note: N, when forms 3 bonds usually has 1 lone pair for donation, when 4 bonds are formed, it has none and +1 charge (generally).
Hope it helps.