I am a the webmaster for a company that provides legitimate services, not products, in which our clientele is completely internet-driven. We have one major site which appears very well in rankings which offers services in all the states we serve. I am creating state-by-state sites that target geographical regions and optimizing keywords for cities and states we serve, which then refer to our main site. The code and design of these new state and city websites are 100% optimized and I am moving to the phase of link-building to hopefully build more PageRank. To maintain credibility, I want to grab relevant links. Somehow, I would like to do this without spending money or risk being banned. What are legitimate practices or tools I can use to take a complete WhiteHat approach without risking my credibility? Thanks.