I haven't done lightning shots in a while, and I never try very hard - just grab some shots through our backyard out the kitchen window. (Use a tripod and stick the lens or lens hood right up against the glass to avoid window reflection.)
Think of the lightning as a giant strobe and set your camera up accordingly. Aperture controls flash - shutter controls ambient. With a low(ish) ISO, you can use a longer shutter speed without exposing the background too much before the lightning. Depending on the strike's intensity, you may still just have silhouettes of foreground structure, or the lightning may light everything up like daytime. (Or like a GIANT strobe.)
Start at f/5.6 and ISO 400 - a three- or five-second shutter speed will give you enough time to catch a strike if your lens is pointed in the right direction and the lightning is frequent enough. If the lightning is too bright, stop down the aperture. Too dark? Open it up. And pre-focus on the farthest object you can.
Here are a few shots I made a while back.
1. 2s @ f/8, ISO 400
2. 5s @ f/6.3, ISO 400
3. 5s @ f/6.3, ISO 400
4. 5s @ f/10, ISO 400
5. 5s @ f/10, ISO 400
