Try unplugging everything that's on that circuit.

That is, remove all the bulbs and disconnect the stereo etc.

Once you've done that see if the fuse still blows.

If it does you know there's a wiring fault.

If it doesn't you know it's a fault with one of the items.

As a priority I'd check the door switches.

It's possible that they're shorting to the body of the car.

Also, it's rare but sometimes the thick wires inside a bulb will fuse together when the filament blows.

When this happens it causes a short and can blow fuses.

See if any of your bulbs look dodgy.
