I too have just delved into the LED light arena. I purchased a multi coloured string at first, but after having troubles making the solder connection, and eventually damaging the strip, I decided to just get a cool white strip. The cause of the damage to the coloured strip was when heat shrinking the solder joints, the strip itself was heated and became brittle causing it to snap while sticking it to the trailer.
The other issue I encountered was to do with the location of the whole for the wires into the side of the trailer. Like a bonehead, I drilled the hole before checking where the awning set when closed. Long story short, the strain relief connector I planned on using protruded too far when it was threaded onto the 3" PVC LB lid I was using to mount the strain relief. I looked everywhere for a lower profile mounting option, and after searching high and low I ended up at a marine outfit and was able to find a gas tank vent that would suite my purposes. I had to remove the screen from the vent cap to allow the wires to pass through and voila, I had my low profile cable pass through.
I placed the LED strip about 2 inches below the attachment point of the awning. This allows for enough light when the awning is rolled up. I mounted a switch under the spice rack which is below the sink/counter. In my trailer, 2013 25bhs, there was a spare 15 Amp fuse for Options The wires were run down behind the fridge, down through the furnace cavity, through to the electrical panel. A separate wire was run down from the switch under the spice rack. I will likely be adding a dimmer. it's almost too bright!
Overall, I'm happy with the install. It was a bit of a rough ride to be honest. A little more planning on my part would have made thin run a lot smoother. But a very doable mod. Thanks to all the other posters who I've been able to pool ideas from! Happy camping! We are sliding a one week holiday on Vancouver Island, our first long trip since we've moved here from Alberta. That's all the holidays I could get with the new job, unfortunately...