Moving averages

Hi,

Im currently in the stage fine tuning my trading plan. I trade with the MAs but every time i read something new they suggest a different MA some recommend short ones and some recommend longer ones like the 200MA.

I day trade so i assume the shorter MA's are more reliable for the way i trade? Do you use different MAs for different time frames? Would it be good to use a 200MA on a weekly chart to get a better understanding of the overall trend or is that irrelevant for trading in such a small time frame. I think most of the information i read is meant more for swing trading which is why i see so many differing opinions.

Thanks!