1. Not cutting losses. ( timing wrong means wrong , very hard to make money without this )
2. Firmly believeing that you are right and the market is wrong. ( you think i think who confirm , last fool theory )
3. Ignorance / Arrogance ( act like know everything but you don't , my suggestion only play stuff that you completely understand )
4. Liquidity ( make sure that the stuff you are buying are stuff that can be sold easily )
5. Over relyance on certain systems i.e "t.a" or "f.a" thus leading to brain lock if things don't go accordingly. ( more often linked to the first problem )
6. Fear ( you know what i mean )
7. Greed ( got profit if possible let it run , don't let a profit become a loss )