I made a line follower robot with PIC16F84A microprocessor equipped with 4 IR sensors. This robot can run on the black and white lines.
Step 1: First Step
Before everything you must know how to make a Printed Circuit Board and how to solder components on it. You also need to know how to program a PIC16F84A IC. Here are the links to good instructables about making a PCB and Soldering: