How do you know when the best time to sell an option is? Is there a doji for selling in addition to buying?

Selling is more of an individual decision based on how much of a loss or gain an investor wants to incur. As we often average into positions, setting losses is more difficult to articulate on a general basis-what is a good stop for us may not be good for another who has a different cost basis on an option. Still, when we see logical support levels that we are using as stops, we will mention those. The reason we use those as stop points (just below support) is that if the stock breaks support, we more than likely want to get out of a position.

The best time to sell an option is when you have hit your target if you have set one up in your game plan. In this market, we look at resistance levels and calculate what price the option should be at (based on the delta) when the stock hits that level. If the stock cannot break through, we will often pull the trigger to sell. If there is no resistance and we are letting it run, we will watch for signs of selling.

We look at the stock itself for signs that we should sell. Signs of topping include a doji after a run up (as you pointed out), a close well off of the daily high, continued inability to break through an intraday high. Volume tapering on a run up shows weakening. A doji on a volume spike can signal a reversal. If we see these, we will move up a stop order where comfortable in the event the stock cannot break through to a new level.