When Buying the dip I often ask myself the following 4 questions:
1. Has there been a fundamental change--negatively, in the underlying asset?
2. Has the price sold off to an area of support?
3. Do you have the cash to prudently accumulate more?
If I can answer No, Yes, Yes then I can safely buy the dip.
"History dosent repeat itself but it often rhymes."
-Mark Twain