#1 starting relatively late with passive stock ETF investing
#2 investing (small time) into single technology stocks during the dot.com bubble with total losses (Lucent, Worldcom, JDS Uniphase)
#3 letting my broker convert european currency into USD, when TransferWise and competitors can do that with much less fees
otherwise my private buy & hold for ultra-longterm technology focused (rather risky & volatile) strategy worked very fine, I must say, however all the U.S. stocks climbed generally over decades now, so very probably not really my own achievement
#1 starting relatively late with passive stock ETF investing
#2 investing (small time) into single technology stocks during the dot.com bubble with total losses (Lucent, Worldcom, JDS Uniphase)
#3 letting my broker convert european currency into USD, when TransferWise and competitors can do that with much less fees
otherwise my private buy & hold for ultra-longterm technology focused (rather risky & volatile) strategy worked very fine, I must say, however all the U.S. stocks climbed generally over decades now, so very probably not really my own achievement