At what price will you start buying bitcoins?
I started buying them when they were $68 and continue to buy them whenever the price dips and I can afford to buy.
The important thing is to never sell unless you absolutely must. Take your profits in bitcoins not fiat currencies. You'll profit far more in the long run.
Everyone has their own idea of what constitutes a buyable dip. I won't usually buy when it just dips to where it was 2 or 3 days earlier unless it has just experienced a dramatic rise like last week. Even then I didn't buy until it dipped to $1600 and started to rise again.
Don't allow yourself to be conned by foolish traders who sold when the price started to fall and desperately want the price to fall further before buying back in.
Long-term, the price will continue to rise.