Really isn't a 'simple' answer. You need to read the labels on the connectors for what they are and positive/negative. If they aren't labeled trace them back to their components at the front of the case. You need to identify the pins on the motherboard they correspond to and get positive/negative correct on all the LEDs.
All the information about the pins on the motherboard should be in the motherboard manual. You just need to orient yourself to the diagram and the physical board.
USB 3.0 connector should be obvious, USB 2.0 connectors are usually keyed with one out of 10 pins missing, match up the missing pins.
There really isn't a completely typical standard, a failing of the industry to be sure.