These are some of the common mistakes I believe that new cryptocurrency traders make. This isn't a complete list and there are plenty of other mistakes that some new traders make such as cloud mining, buying into pump and dump coins etc.
---- Searching for that coin that will make you a millionaire
While I believe it is possible to find that one coin that will make you a millionaire, it is also possible to constantly be investing in coins that offer little value or utility to the crypto marketplace as a whole.
Searching for that one coin that may make you a millionaire in just a few weeks is difficult as most of these types of projects are scam projects and will pump up the price only to run away with all of your money.
A better long-term strategy is finding a good project with a great use case and investing more of your money into a fairly valued project, and waiting until the experts believe that the price is fairly valued. Also, you should do your own research here including technical analysis.
---- No source of income from job, business, etc.
Keep working- find a way to make a decent income and invest some of that money into crypto. If you find your pockets empty all the time, then when you find the perfect investment it will be essentially useless. Continue to make money and work and then when you find the perfect investment you will be able to take advantage of it.
---No diversification or too much diversification
Investing all your chips into just one cryptocurrency or 1 blockchain might not the best way to go. It is important to gauge your risk tolerance and decide which investing strategy works best for you. Typically for me investing in 3-5 projects is the way to go. Some diversification, but investing in 20+ projects will probably kill your expected ROI on projects you invest in.
---Buying a coin at an all-time high- not using any technical analysis or charts when making a decision to buy
Buying at an all-time high is one of the biggest mistakes new investors make in cryptocurrency. It usually isn't very easy to find the best time to buy however, but if you look at the history of the cryptocurrency market you can try and time your purchases better by realizing that with Bitcoin there is typically a new all-time high price every 2 years, followed by a crash of about 70% or more. While, history doesn't always repeat itself there are some patterns happening in cryptocurrency that you should pay attention to.
---Buying coins only based on hype
Buying coins based only based on hype may work sometimes and other times you will lose badly. If you're only buying on hype then you probably aren't considering things like which exchanges the coin is listed on, how much trade volume there is for the coin, and what the team has actually accomplished vs. what they plan to accomplish. Some coins/tokens with low trade volume will be extinct, and even if there is $50,000 of trade volume for a coin in 24 hours, it is still possible that there are only a handful of people trading this coin.
These are just my opinions it is always important that you do your own research before making any new investments.