Tips for finding a good sheet:
If you prefer a crisp sheet, choose a percale weave, which is typically just a 200 thread count to 300 thread count.
For a soft, silky sheet, choose a sateen weave, which is usually 500 to 600 in thread count.
Price counts: Price is a good indicator of whether a sheet really is the thread count you want. Remember, cheap sheets are susceptible to shrinking.