Things You'll Need
Instructions
How to Build Thomas the Tank Engine Tracks
Set aside all of your switch track pieces and adapter pieces (both male-male and female-female). These will be vital no matter what track you make.
Design a plan based around your larger pieces as these are often the most difficult to incorporate if you simply start laying down tracks.
Keep track of how many different track lanes you will have to combine. Never make more lanes than you have switch tracks for or you will end up with dead ends.
Purchase extra sets of switch tracks and adapters. These will make it easier to design a variety of tracks as you will often end up with potential dead ends and situations where the tracks will need special adapters to connect (such as male-male or female-female connections).
Allow your child to "test" the tracks while you're building them. This not only prevents them from getting impatient, but you can also see what they enjoy or what they find boring. You can always rearrange the tracks on the fly.
Consider building a track on the floor instead of on a table as you will have much more room to be both creative and to correct any "miscalculations" in how many pieces it may take to connect your various lanes.