The most important thing you need to establish is what type of lights you need, typically displays use C7 or C9 bulbs, Mini lights, Rope Light, or LED Christmas lights.
C7 and C9 type bulbs are the easiest to fix or revamp. These glass bulbs need to be replaced every few seasons, mixing and matching old and new bulbs isn't what we recommend because the colors/brightness of the bulbs won't be consistent. Hours of burning the lamps, plus being exposed to UV will change colors and the brightness does tend to fade after a seasons worth of hours. So before you decorate with your piece, plug it up and establish what needs to be replaced, if you need many lights we sell incandescent bulbs in bulk for this type of job!
If you have sockets that are broken we also sell sockets that you can replace them with. Sockets have a snap in back and if your sockets aren't making a good connection or are busted it's a quick job to replace them. You can use some small pliers to pull the back out (this usually busts the bottom of the socket but thats ok), once the sockets off work the wire a little bit with the pliers to make it more pliable and put the new socket back on where the old one was and viola you're ready to put a new bulb in the socket.
If you have multiple sockets and breaks in the wire the best thing is to strip the display and start from scratch, we sell rolls of socketed C7 and C9 wire with every bulb spacing that's standard to the industry. You'll need to know the exact measurements of the bulb spacing you have, and we recommend taking pictures of your frame with all the wire and lights on it so you can see how to put the wire back. Most of these christmas pieces are pretty straight forward with wire being taped to the frame and it's not rocket science just takes some patience, if you want anything you're lighting to look it's best never rush it and do it right the first time.
The next most popular type of lights on Christmas decorations is Mini lights, these small bulbs are not as easy to work on compared to their larger screw in style brethren. Replacing burnt out mini light bulbs with spares isn't as simple as one might guess, bulb voltages have to match, the bottom of the bulb has to fit in the bulb holder, and usually there are many steps to replacing a single bulb. Spare mini light bulbs are expensive, we actually don't carry any because of the compatibility issues that plague these small lights so we recommend just buying a new string because you're not paying much more for a whole set compared to loose bulbs. If your displays have many problems with mini light bulbs we suggest pulling them all off and starting new. If you want to go back to incandescent mini lights that works but if you have your frame stripped of lights we suggest going with LED Christmas lights because you're going to get much longer bulb life and save money down the road in terms of power usage and the fact you won't have to replace these LED lights for many many years if the pieces are properly stored.
Rope Light is another product that you see lighting displays pieces and it looks great and honestly is the hardest type of product to fix, if you have a section go out you have to cut out the bad section at the pre determined cutting intervals and splice in a new section. Colors, brightness, etc may not match up when you do this and it can add some total length to your ropelight which can make the displays look slightly "off" if you have sections out and don't want to attempt fixing sections we suggest replacing the rope lights with mini lights or LED christmas lights.
LED Christmas lights function about the same as mini lights and are no where near as fussy when it comes to durability and longevity. We suggest always stepping up to LED lights when you can because they will just be much easier to work with and give you less head aches!
I hope this gave you some insight into sprucing up your Holiday displays, check out www.aachristmas.com to see all the bulbs and light strings you'd need for any display project.