The most important thing to know when collecting coins can be summed up in this phrase: “Either know your coins or know your coin dealer; and it’s best to know both!”
Buying from a trusted source as opposed to one that is unreliable can save you both money and stress. Also, it is important whether you are collecting coins, or have a collection you are looking to sell, to keep the coins as original as possible. This means to avoid any cleaning of collector coins, as this very well may decrease their value, while also storing them in dry and air-right places, where they will be protected from different elements.