the first hand
the only thing that I would have done different was to raise on the flop to find out if he has an over pair and if he does he will probaly reraise me and I will know that my 4s are no good and either throw them away right there or throw them away on the turn. I he just calls me on the flop then I am pretty sure my 4s are good and I will go with them. But since you won all his money I guess you did everything right
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The second hand
theres not much you could do here. But I might have raise before the flop since
in a four handed game isnt that bad and you are in bad postion so you need to probaly only go against one opponet. Unless since it is a low limit game people arent folding to raises. Also you could have reraised one the flop because you can be pretty sure that you have the best hand becuase he would have raised it preflop if he could out kick you. And then in he caps in on the flop you know that he probaly has two pair and get ready to lay this down pretty soon. Other wise this was just a unlucky hand that you ran into an idiot who likes to raise with straight draw.