Settings with TTL flash

I'm not quite sure which mode to shoot in when using a TTL-flash. Can I set the aperture manualy and set the shutter speed to auto or should I set both paramatures manualy for the flash to figure out when to shut off?

I think TTL will work regarding the mode you are shooting in, either auto or manual.

The mode you shoot in depends on what you're trying to shoot.

The only concrete rule is:

the shutter speed cannot exceed the maximum flash sync speed.

I normally shoot in full manual.

Aperture priority, if depth of field _or_ balancing ambient light is important.

Shutter priority, if freezing action is important.

Auto = major chance for bad photos underwater (cameras make dumb assumptions because they're optimized for land shooting in sunny conditions)

TTL works fairly well for macro. But, can be easily fooled when shooting wide angle.

Many digital photographers shoot with manual strobe settings: varying the strobe power, strobe to subject distance, adding a diffuser. Instead of shooting TTL. Learn how to use the histogram display on your camera.

Thank you for your replies!