I don't look at support or resistance at all with a trailing stop, and depnding on what im doing at the time, not even with the initial stop.
It all depends how you are trading. If you are trading agressively the initial stop might be so tight that you have 25%+ of your total equity on the one position, or it might be so loose that you are only commiting 5% of capital to a trade.
It doesn't matter how you do it. There is no right or wrong trailing stop, it's not black and white. Just do whatever works for you. If you can't let go of much open profit, use a tighter stop. If you don't check your account every 5 seconds and are prepared to take whatever the market will give you, use a wider stop and ride the big trends.
The stop will ultimately determine the average length of your trades, so keep that in mind.