What will you use the rifle for? If long range varmints are in your future, then a variable scope with a max magnification between 12 and 18 should fill the bill for about any reasonable use. Higher magnifications are very often not usable in the field due to mirrage or a poor rest. Get the best scope you can afford - a used Leupold or Burris is far better than a new BSA, etc.
The
classic load for the .22-250 is a 55-grain bullet, but there are many choices. For the longer ranges the 55s work well, but many shooters like the newer 40-grain speedsters. The latter shoot as flat and drift the same as the 55s out to 400 yards. What really matters is what load shoots the most accurately in your rifle.