Depending on condition of your finish you may need a wet sand (if heavily oxidized). If lightly oxidized you should be able to cut out the finish with a liquid compound applied by rotary buffer, follow with a polish to remove swirl marks and bring out the shine then finish off with a good quality wax. Keep the buffer moving and let it do the work for you. As long as you don't camp out on the decals they will be fine. Step back and admire your new found shine.
There are many good products out there that will get you the results you're looking for. I've used Meguiars number series products for years with great results. Their Flagship Marine Wax works very well too.