Quality Link Building

We are looking for someone to help us with link building (for website SEO). It important that the links are natural-looking, diversified, good quality etc (and certainly not from link farms) - so we will pay by the hour rather by number of links (recognising that a significant amount or leg work might not lead to anything). We will have input on link prospects to pursue but would expect the person to be pro-active too, have a good understanding of what they are looking for, and communicate well with us (and with prospects on our behalf). Looking for an ongoing basis of 3-5 hours per week.