As Zen said, check the grounds first, then probably second, and maybe third. When it comes to brake lights, sometimes the switches on the master cylinder will fail as well. Step one, with the key on, see if you're getting power to the switches (check using a test light first at the terminal of the fuse panel headed to the brake lights, usually a black/red wire that disappears into a hole in the trunk area above the left fron wheel arch,and then on the connector/terminal of the switch itself with a test light hooked up to a good ground or, if you're really high-tech, with a multimeter. If you're not, head back up to the fuse panel and check the fuse/wiring to the brake lamp switch.. If you are getting power, and you've still got no brake lights, the culprit is often times the switch (although, we can't rule out those pesky grounds or bulb sockets). Another little trick to cure acting up lighting on any old bug? go through the fuses on the fuse panel one at a time, twisting each one and then check your lights again. I can't tell you how many lighting and other electrical woes we performed this little magic trick on successfully when I worked at Lockhart's. The fuses can get a small amount of corrosion between them and the terminal on the fuse panel, causing the same basic symptoms as a faulty ground.
Good luck hunting.
