All my 'coin collecting' is done through metal detecting. If you seriously want to collect coins though it is not really the right way to do it. Most coins I find (95%) are copper/bronze from 1700 onwards and are in such bad condition that most coin collectors wouldn't touch them with a barge pole. If they have enough detail on them to make an ID then I am happy as I use them to produce a report to the farmers of what I've found. Normally I spend hours trying to spot the edge of a 'bust' or part of Britannia amongst the corrosion to make that ID. Occasionally you find a silver coin, bu tagain unless you go back to a time when they were almost pure silver, they also can degrade very quickly. I have found a handful of hammered silver coins, these are generally worn almost smooth but are very exciting to find. I'm still waiting for my first piece of gold and my first Roman with enough detail left to ID.