If you do not have a strong graphics card (GPU) that you already use for gaming, I would recommend not getting into the mining game. If you only have a CPU, it is very hard to mine any coins. It is not the easiest task configuring and optimizing a machine while still keeping it cool and not noisy and not to mention doing some maths calculations on electricity costs to still be profitable. It is way easier to just buy a coin from the exchanges and track the price whether it goes up or down.

To determine which altcoins have the most potential, a good resource to start is to look at CoinGecko. There are many metrics on the website giving you stats on the developer activity, community strength, trading volume, market cap etc. You may use these stats to make a judgement on which coins may be strong.