I bought a cleaning kit , with swabs and the solution, it works well
For stubborn spots I may have to repeat more than once, I check how it worked by shooting the sky at f/16, and repeating.
Get a feeling how the swabs and solution work by cleaning another smooth surface before trying it on your camera, I do this on my phone screen, just for practice, as the solution my not evaporate and may leave streaks, how do you clean those? just another pass, with less solution on the swab
My D800 was purchased in 2012, I have cleaned the sensor three times eliminating all the spots and with no ill effects