But you can't buy at the absolute bottom, only if you're really lucky. Almost always when you buy the price will go lower again afterwards, and probably more than you are comfortable with. So why not just choose a price you think is acceptable based on trend analysis and stuff and simply place buy orders there? I'm pretty sure you will get a better price this way rather than waiting for all your indicators to align and you are 100% sure we're in an uptrend that will continue for a while.
Once you have identified the long term trend (hint: UP) then you just want to get in at a good price. Bottom picking is a dirty business, so just buy when you think you're getting a good deal, and then if it goes lower take advantage and buy more.
Assuming (hoping) we hit bottom the other night, I got in at about as decent a time as I really think I could have. I really didn't think it'd fall below 450 or so (blind luck guessing), but I wasn't going to wait for it to hit that number. Bought in at around 500.
Really all I can do now is wait to see whether it pans out or not.
Cheers!