Dear Supreme Leaders, Grand Moffs, and Sith Lords,
First, I believe congratulations are in order for having built and then revived a powerful and formidable Empire. Your ambition and vision are truly incontestable and to be revered.
The purpose of this letter is to suggest that perhaps it is time to adopt a new strategy, as your repeated attempts at building super-weapons invariably seem to backfire. The destruction of six planets total is certainly an accomplishment, but the Rebels have a way of blowing up your super-weapons, yet you stubbornly rebuild, believing that the next one will be stronger. Unfortunately, all three have met the same tragic end.
Before I continue, I would like to point out how unbelievably impressive it is that these three aforementioned super-weapons (Death Star, Second Death Star, Star Killer) were constructed in total secrecy. Such an incredible development boasting the finest advances in architecture, technology, and military prowess seems that it would attract attention in several galaxies. And with the amount of manpower needed to materialize such a thing, it is truly remarkable that the hundreds of designers and builders needed were able to carry out this feat in total confidentiality. I make no assumptions on where they all are now, though rumors exist of previously offered retirement packages on the planet Alderaan.
Perhaps this is presumptuous of me, but it seems that the greatest success the Empire has had in subduing the planets was in the early years where coercion, deception, and shrewdness strategically placed some of your greatest minds in highly influential positions. For example, the manipulation of the Imperial Senate to elect to power the late Palpatine, was truly ingenious, and it seems that your regime enjoyed years of blind following before sparks of rebellion began. A return to these more diplomatic and subversive means of conquest might be to your advantage as you start up your new regime. It's not that fear and military might don't produce results, but it seems that you faced no opposition until these tactics became your main ones.
I would also like to point out that the Empire, vast and varied as it is, seems to have a few moles. The Rebels and Resistance do have a way of attaining your plans against your will (or sometimes in line with your will), but we have yet to know of an Imperial spy within the Rebellion or Resistance.
Your tireless efforts to dominate are impressive, and you truly are the definitive examples of "If at first you don't succeed, try and try again."
Please don't blow up my planet.
A concerned, loyal, and in no way questioning citizen of a galaxy far, far away.