The process is not that difficult. You need 2 things content about the type of business or product you are promoting and mention of the location. The other thing you will need is backlinks with the location in the anchor text. Keep in mind not to over optimize your anchors or overuse of keywords.
Say you are trying to rank for "Dry Cleaners in Detroit". You don't need to or want to keep using "Dry Cleaners in Detroit" as the keyword in your content or anchors. You should use keywords that would be used naturally within the content. Content will be on dry cleaning so you will use words that will be about dry cleaning and related services. You will need to mention the location you are trying to rank a few times within the content.
Anchors should be natural as well. Most should be branded and generic. But some should be keyword targeted and branded with location, like: " http://#", "http://#"
Embedding a Google map of the location, linking out to government and other local websites, helps as well.