You simply can't tell for certain.

Perhaps certain indicators will help. However, when markets are going down like this on a daily basis I think the wisest thing to do is to pick a few coins with good long term fundamentals, and simply dollar cost average.

That is the safest way to go long on a coin in a bear market, imo. You're ensuring that you don't buy at the top, nor do you miss out on the opportunity to load up cheap coins.