Don't forget that search/internet marketing is multi-faceted. Traditional Marketing 101 teachers would say to build a comprehensive plan for marketing. Don't just work the online factors, but create a sound strategy around offline marketing, using ideas like postcards, trade magazines ads, phone/sales work, word of mouth and additional …

Another way to find places you can build links is by using a link intersection tool. These find sites that link to "competitor a" and "competitor b" but not to you. Theoretically, if they link to both of your competitors, they should be willing to link to you. Moz, Ahrefs …