In normal circumstances, it is not advisable to buy when the market is falling, if you get in it is like catching a falling dagger.

Not exactly - if you think something will rise long term then it makes sense to buy and if you spread your buys out you can make sure that you don't buy everything towards the upper end of a fall.

Obviously you don't want to buy immediately if you think something will fall further.

This all applies to my long term investment strategy - obviously if you are day trading then the considerations may be slightly different.