can I ask why concentrate on two different websites, without knowing what you would be selling / listing its a bit difficult, but as Moosa said having the same address / telephone number google might think they are the same business and link them, but more importantly why do you want two different domains.
In my opinion your spending time creating great unique content on two different sites, managing two different domains etc - why not simply put all the content onto one great site (rather than two good sites) and 301 one url to the other. It would be easier to get one great website higher up the SERPs rather than trying to get two good sites to link.
All your efforts would be to get links to one site, rather than two different domains, you would be ineffective splitting your domain authority (doesn't quite work evenly like that).
But if you really do need to have two different websites and are willing to put in the extra work, the best thing to do would be get them listed separately on Google places (ideally at a different address), have different contact details, names on their so that search engines don't try and link them.