Word of mouth is great when you're established, but is obviously much harder to come by when you're just starting (or re-starting) out. Organic SEO is a good medium-term strategy, but takes a while again for it to get going. PPC is good for getting local business, however most PPC keywords in our industry are saturated. Lead generation is a good one, as you invest some money and usually get leads within days - however in my opinion the best approach would be to combine all of them. Work on your website (build keyword-rich content), invest an amount in PPC and organic link building (or even better create some 'linkbait') and make your clients happy to get the word of mouth going. That way you're not putting all your eggs in one basket, and it allows you to see which techniques work for you.