The biggest mistake I made was just investing wildly without having much knowledge, being new. So I suggest just keep those 700 in Bitcoin, and then do a lot of research. The key is to be patient and don't fall for, "Lambo, this coin is going to moon."
That's every newbie's mistake. They join the van of Lambo songs and get easily swayed. The best way is to observe for several months if possible. Losing out on what could seem like a FOMO driven coin or investment can save you a lot of heartaches especially when you don't understand trading signals.