I usually go for a standard build:
-Wait for a world without snow.
-Search for a big beach as soon as I spawn.
-Build a big wall of dirt to block the zone I like
-Search for some coal
-Start 4 furnaces in the wall area and build a glass house to plant wheat. Big irrigation project starts too.
-Build an observation tower next to the glasshouse, light some wood on the top floor, so that it burns forever. Makes a good lighthouse.
-Substitute the dirt wall with a glass wall
-Start a mine complex. I'm pretty OCD, so I make a few signs and label all my mine shafts. I also plant signs when I hear monsters, to pinpoint dungeons.
Usually when I get bored after a few hours, I start building a glass-bottom under a lake. Looks incredibly awesome to walk under the water