It also helps if you repay their time with a little patronage. It doesn't have to be an expensive item, but it proves that you are sincere about collecting. In most cases, the value of a stamp is determined not only by how rare it is, but also its condition and centering, so determining the grade of a stamp is important. The following guide should help. VF - Very Fine.
Later issues have complete, undisturbed gum with no faults except hinging.
The colour must appear fresh and bright with no fading. The paper must be free of all defects. The design will be well centred. The cancel is light, clear and well positioned. While not mandatory, a Circle Date Stamp is preferred with some collectors also preferring a light corner cancel leaving the design clear.