Any advertising spend that produces a profit (over a reasonable time span) and increases a 'stable' turnover is good.
The trick is to find out which advertising method works the best for YOU...that's the 'million dollar' question.
Leaflets, canvassing, van signage, facebook, Google Adwords, Google Business Plus, word of mouth, referrals, posters, tv, radio...the list is endless!
You have to find out what works best for YOU (trial and error). And it will be different, depending upon location, types of customer, what you are trying to achieve, blah, blah, blah
Once you find the magic formula, then go for it...