Up to a few years ago, most Lego kits came stamped with the legend "Ages 5 to 12," which doubtless dissuaded many adults from building modernistic Lego masterpieces in their living rooms. Today, though, Lego buckets are more appropriately designated "Ages 5 to 99," meaning you can raid the Lego department of Toys 'R' Us without having a sales clerk look at you cross-eyed. Here's how to indulge your newfound Lego jones:
Stick with basic bricks. Generally, Legos are more fun when you don't follow the step-by-step instructions telling you how to build a Death Star. If you're the type who doesn't like his creativity fettered, buy an assortment of basic bricks (you can usually find bins of 1,000 pieces or more for about $20) and build what suits your fancy.
Buy some baseplates. For practical reasons, when a freeform Lego sculpture reaches a certain size, it must be anchored firmly to the ground with a baseplate. You can buy plates in a variety of colors and sizes, ranging from a few inches square to a foot and a half on each side. If you're building something huge, you can easily join the baseplates so they cover your entire floor.
Break the rules. Technically, Legos are only supposed to be assembled in perpendicular fashion, but with a little ingenuity (and lots of experimentation) it's possible to build structures incorporating diagonals and hinged, swiveling pieces. If you want to try your hand at this, it helps to collect as many long, narrow bricks as you can find, as these are more suited to rococo styles.
If you don't like what you've built, tear it down. One beauty of Lego structures is their impermanence; when you get bored with your latest masterpiece, you can disassemble it carefully piece by piece (or smash it with a chair) and build something even better. Just be sure to take a picture first, to preserve your creation for posterity.