since all my photos are from the digital camera they are quite large for upload 3-4meg, so i resize all of them. you can use e.g. ms pic manager to do that or paint or other utilities. there are 2 numbers width and length(pixels) that gives you the dimension - i roughly reduce the size percentage wise so that the width comes below 1000 pixels. that reduces the pic size anywhere from 300 - 600kb. usually it is advisable to keep the pic size below 1meg (1meg=1000kbytes) so that people can view it on small screens: it downloads faster. some people have slow inet connections too - keeping the size smaller speeds up viewing. also when the screen is small and pic is oversized - you'll need to scroll right/bottom to see the whole pic. and then when you can't see the whole pic at once the whole effect is lost so to speak.
of course you don't want to make it so-o small, that you can't see much detail either.
