I second Biased Turkey's idea about checking out Katy's Nscale layout...it's great and I'm still looking it over and applying his ideas to my own layout.
There are plenty of good information right on this website. You might consider getting a trackplan book from Atlas or other track maker to mull over some plan ideas. Also, check out the past threads on what type of track to use (flex vs. snap or sectional track), DC vs DCC operations, what type of layout you'd like to run and build. It takes a while to finally decide what you want to do...but believe me...it's easier changing plans on paper than taking whole sections of track and scenery apart when something doesn't quite turn out like you thought. Also, whatever scale you using, visit the manufacturer's websites like Atlas, Kato, Walther's for example...there is a lot of information about track, scenery, buildings, and of course engines/rolling stock that might spark ideas you haven't thought of yet that you'd like to incorporate into your layout.
I know from experience on my own layout...I started quick and fast just to get something on a table for the kids and I to run without much forethought...now I wish I would have planned much more and considered each building I wanted to add and how I wanted the overall "look" of the layout to be. I'm spending a lot of time going back over places once considered "done" and re-doing them to improve on my earlier and very unschooled efforts.