The punch-down connectors where the wires connect to the back of an RJ-45 jack are usually color-coded for both the 568A and 568B standards. To insure that the wires connect to the correct pins visible at the front of the jack, one follows the scheme at the back of the jack, as the wires usually cross--have an additional twist--inside of the jack.
Choose which color code standard you want for the jack and wire the plug to the same standard as the one used for the jack for a straight-thru connection and the other standard for a crossover connection. Directions and pin-out drawings for wiring the plugs are in How to Make Your Own CAT 5 Twisted-Pair Network Cables at http://duxcw.com/digest/Howto/network/cable/cable1.htm. The preferred standard is 568A, but it doesn’t make any difference in the functioning of the cable which standard you use. The wires must not be untwisted more than one half an inch at either end of the cable. You would use a straight-thru connection for the cable between a PC and hub. Horizontal wiring (in walls, etc. and for runs longer than 3 meters) should be solid core and the plugs have to be designed for that kind of cable. Plugs, jacks, and cable have to be rated for CAT 5, 5e, or 6 operations. I currently use CAT 5e and may switch to CAT 6 when it becomes affordable. All three are backward compatible and support 10OBASE-TX and 1000BASE-TX networks. CAT 6 does it better than 5e, and 5e is better than 5. Larry