Hello and welcome.

It's real easy to
not make a lot of money buying and selling coins. There's an old, tired joke that the easiest way to make a small fortune in coins is to start out with a large fortune. But it can be done, as is evidenced by the fact that coin dealers exist, and that there are tens of thousands of people out there making a living out of buying and selling coins.
There are three "easier" ways of making money coin flipping:
- Buying in bulk, and selling individually. This is, in effect, where many coin dealers get their main profits from. A collection bought at bulk rates might be hiding gems not initially noticed when the collection was first bought, and you always get more money by selling coins one at a time than by selling in bulk. Of course, the issue here is getting your hands on high quality, high quantity bulk coinage.
- Cherry-picking. This is the term used to sort through large numbers of coins (eg in a dealer's scratchtray, or even rolls of circulation currency) looking for the rarities, errors and oddities that stand out to you, but no-one else looking at those same coins had noticed before. This does require you to have considerable knowledge about what actually are rare and interesting coins worth cherry-picking
- Knowledge of multiple markets. I know several people, both dealers and collectors, who have made nice money by buying coins in one market where they are unappreciated (and therefore cheap), and selling them in another market (where they are well known and valuable). This is usually across international borders, perhaps also with a language barrier as well. Example: I have a Dutch friend who lives in Australia; he often sees Dutch coins going cheap here because they're "just another foreign coin" nobody cares about. He can buy them here cheap, and sell them for a profit back in the Netherlands next time he goes back to the old country. While he's over there, he can buy Australian coins cheap, and bring them back to Australia for profit. Do this well enough, and you can make enough profit to pay for the plane tickets. I have a couple of other friends whose stories are the same but for which you can substitute "British/Britain" for "Dutch/The Netherlands". This of course requires you to be familiar with two different coin markets, and have a reliable means of shipping coins between the two markets - Ideally, to minimize shipping costs by taking the coins with you while travelling overseas yourself for family/other reasons.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis