Consider case cooling and working conditions before considering case aesthetics. A case that looks like a neon alien ain't worth jack if you can barely work in it, or if it has awful airflow.

Install the mobo, CPU, cooling devices, RAM, PSU and video card then do a test to see if it turns on before hooking up optical drives, hdds, sound cards, ect. Make sure the core components are functional before putting it completely together.

Install RAM and the CPU before mounting your mobo in the case.

Keep the case open on the first turn on to make sure the fans are working.

If your vid card requires additional power connectors, make sure they're hooked up before turning the machine on. That horrible BEEPBEEP can be nasty on the nerves, even if it's just a vid card complaining about your not hooking up the power.