the hardest part is installing the hardware, the wiring is easy. the problem people come into is when they don't fuse anything or try to draw too much power through a switch or wire that is not rated for all the power. for connections get either male/female connectors or butt splice connectors. if you are just doing windows and locks then tap off the constant 12v just before your ignition ( best is behind your fuse block straight from the battery but its a bitch to get to sometimes). when you tap this wire put an inline fuse holder that accepts the same type of fuse as the rest of your car ( so that you don't have to keep an odd ball around, and incase you need a quick replacement for a more critical system.) then use a fuse that is rated for the factory system, with multiple systems you can just add the amp rating, I.E. windows 10 amp + locks 10 amp = 20 amp. keep in mind that the factory system probably did not have just the one item on that fuse so I would say a safe bet is to just use a 10 amp.

if the factory switches we not run with a relay to the motor/actuators then you don't meed relays, but if you are using 2 different systems I.E. the spal window motors with factory switches It is easier to use relays ( if you know what all the ratings are and how to calculate an electrical circuit you might be able to use both without the relays but when in doubt use a relay) the relays use a low current ( your switches ) to control a high current ( motors ).

if you use more than 1 relay and the power wires are hooked to the above mentioned fuse holder up the fuse to a 15 amp ( try it with the 10 amp it may be good enough) just remember to go with the smallest fuse you can without blowing every other time. on most automotive systems ( fuel management excluded ) like you are dealing with a 5 amp higher fuse than what is exactly needed is not going to cause an issue.

it may be some work but it is sooooo worth it to have power options.

if you have any mechanical aptitude,save your money,learn how to do it yourself,and remember that no body gives a shit how well you car is worked on as much as you.

I have been to the shops around here for car alarms and auto accessories and here's what up when they so the work

1 shop said my trunk pop actuator kept opening the trunk while I was drivingdown the road because of a short in the wire= bull shit the actuator was adjusted to close to the limit and opened when i hit a bump loosen a screw, move the actuator 1/4 inch and tighten screw= no problem.

window express module and alarm installed= fried aux output on alarm brain

took that problem to another shop to fix and they fried my window module when they hooked it back up ( I gave them the factory install instructions but they never took them out to read them, because they are "professionals")

i had warranty repairs ( notice I had it done, the shops would not help because they were not the dealer for the product) and reinstalled the units= not a problem since I did it myself.

once you see how switches and relays work ( hint, a relay is just a switch that is flipped using the electricity from the actual switch you push ) it is like changing a tire.

get a book from borders bools and read a little you will be a million times happier.

I do all my own electrical now.