10 MISTAKES YOU SHOULD NEVER DO IN CRYPTO TRADING 
LET'S START
1/ Don't be so greedy,as something is better than nothing.If you get 10% profit then try to sell out and exit.Otherwise you will lose all your money if you want more than 10%.
2/ Never buy altcoins when bitcoin price is unstoppable.
3/ Never invest your all money in one coin you must diversity.
4/ Don't sell your coins at loss,don't get into panic sale.Because if you brought protensial coin, then don't sell your coin if it dump.Because it will grow again after some days.
5.Never invest all btc in altcoins keep some btc in wallet for right time.If you like one coin most,don't invest your all money on this coin.Keep some btc for right time.
6/ Always make your portfolio, decide part if short and long time.
7/ Don't sale your long term coins at panic sale.You should hold your long term coins for 1 or 2 years.
8/ Don't do trading with your emotions keep them aside.
9/ Don't do day trading without proper knowledge.Before learning day trading don't go for it.Otherwise you will lose your all money.
10/ Never buy coins at their all time high price.Don't buy coin at their high price, wait for dump and buy at deep.
Guys if you follow this 10 strategy, then I'm sure you will be safe from losses.
Ive actually made some of these mistakes, especially greediness is the worst of them all, cause I can remember that as a newbie I would usually like to make lots of profit and end up with loss. But I later took correction and stopped that and started taking whatever I see. My friend also lost a lot due to this same greed issue. LET'S START
1/ Don't be so greedy,as something is better than nothing.If you get 10% profit then try to sell out and exit.Otherwise you will lose all your money if you want more than 10%.
2/ Never buy altcoins when bitcoin price is unstoppable.
3/ Never invest your all money in one coin you must diversity.
4/ Don't sell your coins at loss,don't get into panic sale.Because if you brought protensial coin, then don't sell your coin if it dump.Because it will grow again after some days.
5.Never invest all btc in altcoins keep some btc in wallet for right time.If you like one coin most,don't invest your all money on this coin.Keep some btc for right time.
6/ Always make your portfolio, decide part if short and long time.
7/ Don't sale your long term coins at panic sale.You should hold your long term coins for 1 or 2 years.
8/ Don't do trading with your emotions keep them aside.
9/ Don't do day trading without proper knowledge.Before learning day trading don't go for it.Otherwise you will lose your all money.
10/ Never buy coins at their all time high price.Don't buy coin at their high price, wait for dump and buy at deep.
Guys if you follow this 10 strategy, then I'm sure you will be safe from losses.
As for the number four, I think anyone can sell their coins with a little loss to avoid more loss. You can still withdraw and wait for the right time for getting back in again, and if youre lucky you will regain the little loss. If you leave it for so long, you might regret, if it wasnt your plan to hold long-term.