LED strips seem simple https://myeverlights.com/. You peel the backing, stick it on the wall, flip the switch. Give it 48 hours: one end is dangling off the shelf while the other end glows at half the brightness of the first.
Sticking issues first. Even the best tape won't grab well on textured paint, dirty wood, or greasy surfaces. Wipe the area with isopropyl alcohol and give it time to dry. Aluminum channels or mounting clips hold far better than tape alone on rough surfaces, and a channel doubles as a diffuser that blends the dotted look of individual diodes.
Dimming at the far end = voltage drop. Somewhat counterintuitively, long runs of 12V strips lose power along the copper traces. Once a run reaches about five meters or more, the end starts fading. Either power it from both ends or choose 24V, which handles long distances much better.
Many buyers stumble on power supply sizing. To get it right: add up the total wattage of the strip, then choose a power supply at least 20% larger. Running a power supply at full load stresses it, shortens its lifespan, and can even make it run hot.
Next, there is cutting. LED strips are only designed to be cut at the marked copper pads (generally every three diodes). Snip anywhere else and that section goes dead. To rejoin a cut strip, use solderless connectors or solder carefully.
Don't forget about moisture. For bathrooms, kitchens, and porches, choose a silicone-coated strip with an IP65 rating or higher. An ordinary indoor strip placed by the sink won't make it through the season.
Finally, think ahead when choosing controls. A simple remote adjusts color and brightness; an app brings scheduling and music sync. Some RGBIC strips show two or more colors at once along a single strip - a nice touch for a feature wall, though an unneeded extra cost under the cabinets.
Map out your plan, recheck your measurements, and installation will go smoothly.