Marketing two sites on the same server

I'm planning on developing a new site, and hosting it on the same server as my established one.

Is there anything I should keep in mind when doing off-page SEO for this new site? If I use the same backlink methods I used to market the first site, will this be counter-effective? For example would G penalise me for putting a backlink to both sites in my sig on forums.

Or would I be better off just hosting the new site in a new server all together?

Any advice would be appreciated.