What does a publisher look for in a manuscript? Is there a proper format or a general set of guidelines one should follow?
Yes, basically. But you should always check the specific guidelines of the publisher you're submitting to. In most cases it will either say nothing (in which case use that format), or link to that page as an example.
...at first glance, format... after that, the opening... if the first is noticeably 'off' and/or the second doesn't 'hook' the reader, it's unlikely that s/he will bother to go any further... yes... what banzai provided a link to is a good general guide, but as he added, you should always follow each agent's/publisher's specific submission rules 'n regs, if they differ...
That link was enormously helpful. EDIT: Nevermind on my question, I didn't browse the page enough! So I'll just leave it at thanks.