A thought that before learning to spot a fake I'd start to carefully examine the characteristics of the real deal. Found an auction house website and examined images of VF & EF 1787 shillings. Here are images of the obverse of the first three examples I saw:
Yep - There are two variants: The dot over the wreath and the dot not over the wreath. However, the position of the text is slightly different between all three. Check out where the last "I" of "III" ends and the "D" of "Dei" begins. Is one of these non-genuine? Were there different dies with different text positions?
Similarly, I examined the reverse of each of the coins:
The dot between "F" and "D" at the top of the coin in example two is lower than in the other two. Incidentally, this is the non-dot coin. Is this typical of this variant? Furthermore, re text "A.T.ET.E.", there is no evidence of the dot before and after "ET" in the first example. Is this wear? A variant?
It's going to be hard to try and spot fakes without knowing everything that's within the range of acknowledged, acceptable variation and their acceptable combinations! I have much learning to do.