Mistake #1:
Never engage in medium or long-term trades with shitcoins.
These highly volatile assets can be removed from exchanges at any moment, dropping sharply—sometimes by as much as -50%! They’re unpredictable, defy technical analysis, and swing wildly up and down.
Shitcoins are strictly for scalping or short-term trading, and using a stop-loss is absolutely essential.
This isn't something that for me considered as "automatic" already because we know how risky these shitcoins are. Unfortunately, there are some who are choosing to hold the coins that they bought because of the hope that at some point, it will go up again and they will end up in profit still. In trading in general, you should always put a stop loss whether you're trading Bitcoin, Ethereum, or shitcoins. This is one of my mistakes in the past and if I don't look at my monitor for a while, I always put a stop loss.
Mistake #2:
Avoid overtrading at all costs.
Just because you’ve exited a trade—whether it was profitable or not—doesn’t mean you should immediately jump into another one. Sometimes not trading at all is a win in itself.
Excessive trading increases your chances of losses and drains your focus and patience.
One of my biggest mistakes last year when I started trading. There are times where I make 10 trades per day, and it really drains your energy not physically, but mentally. This year. I will make it a habit that I will make only at most 3-5 trades despite on whether I win or lose on my trades. I will also take note that I will learn in every trade that I will make because I believe that "every candlestick" has a sign on whether it's a bullish or bearish.
Mistake #3:
Don’t buy newly-listed coins on exchanges, especially if you’re a beginner.
You’re at risk of becoming liquidity for early investors or teams dumping their tokens on you. This has happened many times with freshly-listed coins—beware of the hype!
I've seen some traders that are making short positions on newly listed coins that has been listed on futures as well, and it works pretty well with them because as soon as the token gets listed, many will sell their tokens hence, putting the price down and it will be a profit for those who went short. Still, don't touch those newly listed coins like what OP said if you're a newbie, or they will dump in your face.