Carol I have eighty-odd in one album but have looked at the sizes and they are nowhere as large as you say yours are (270kb). I do not usually resize mine, just load them and let Yuku resize them if necessary. I just take them with the normal camera that I use for ordinary photographs so do not really do anything different. I certainly don't reduce them for the purpose of putting them on Yuku.
Perhaps someone who is technical can answer this one?

Helen