The gold standard for any electrical work that is either in the US or other countries which don't have any more detailed description is the National Electrical Code 2011 (National Fire Protection Association National Electrical Code) . This is a huge book and for all but the professional, probably not worth the purchase price. But, when in doubt, it is where to look.

As a minimum, get some reference material. I highly recommend 2011 Dr. Watts - Pocket Electrical Guide which is a little pocket guide based on the NEC. For more home wiring projects, it will tell you all you need to know.

Grounding is the first issue that tends to get neglected. You may thing that because you are off-grid you don't need to be concerned with the ground. Nothing could be further from the truth, particularly if you system includes something up in the air such as photovoltaic panels or a wind generator. Make sure the frames of your PV panels are grounded as well as the frame of your wind generator. Grounded doesn't mean connecting one of the power leads from the panels to a ground rod. The ground must be a separate conductor or you are asking for fry some equipment and possibly yourself. This is the same as the neutral (green) wire on typical household outlets.

PV controllers, inverters and such will also have a separate ground terminal. Make sure this is connected to your ground rod and not connected to one side of your battery or inverter output.

Next on the I'll do it later list are circuit protectors. That is fuses and circuit breakers. If budget is not an issue, opting for circuit breakers is the best option. A regular circuit breaker gives you the additional advantage of a disconnect switch and, of course, they do not need to be replaced if they trip.

A good rule of thumb is to use fuses where they should never blow, circuit breakers in other places. For example, I have a 400A fuse between the battery bank and the loads. The batteries are easily capable of delivering 400A and the wire in the circuit is large enough to handle that overload but standard operating current would never be close to that level. And, of course, a 400A circuit breaker is very expensive.

If you have a 12V or 24V battery system, blade fuses like are used in cars offer a cheap alternative to circuit breakers. Additionally, there are auto-reset circuit breakers that are inexpensive and will fit in the same socket as the blade fuses. They are rated at up to 32 volts.

If you have a 120VAC or 240VAC inverter, treat its output just like regular house wiring. That is, run three wires to the loads and install a regular breaker panel. Make sure you ground the neutral at the breaker panel. As is normal with regular AC circuits, the neutral should be connected to one side of the power at one and only one point. That point should be in the breaker box.

Breaker sizes should be appropriate for wire sizes. For lower voltage circuits you may want larger that required wires to decrease circuit drop but, in no case, should the breaker size be larger than the safe current capacity of the wire. One place where this is overlooked is combining multiple strings of PV panels. Each string should have its own fuse or circuit breaker.

Finally, use wires of the appropriate colors. I leave that you to you and Doctor Watts as I happen to disagree with some NEC changes that took place in, I believe, 2005. The most important part of the picture is make sure it is easy for you to distinguish between your low-voltage DC circuits and your AC circuits.

There is so much more that can be said here and what that is will, of course, depend on your particular installation. But, this is a start.