Thanks alex. Always helpful. Just to clarify I would always need a tripod?
definitely, your probably going to use shutter speeds that will take some seconds
Only if you plan to utilise longer shutter speeds for effect (e.g. light trails) and/or your camera can't handle high ISOs well. Call it heresy if you want, but I don't carry a tripod any more unless I solely intend to do landscape or night scene photography where I want to capture trails of motion. Otherwise I'm able to handhold using high ISOs. See example below:
ISO 6400, 1/160 at f4, 20-35 2.8 at 20mm.
PP - shot as jpeg; resized to reduce file size to load onto Flickr...