Monero

I am trying to buy Monero for the first time, but I don't know which way to the best and easiest and hoping to get some guidance. I have Cake Wallet and I can purchase Monero through there, but I can't tell if they have the best rates. I also came across Haveno, which is a decentralized Monero exchange, but I don't know if that something I should use. There is also Trocador. Of all of these options, which one would be the best for begineer? Note: I am just trying to purchase a small amount of Monero ($10-20), nothing big.