stop losses??

Since it is a Sunday I thought I would ask peoples thoughts on stop losses.

I am currently looking at developing a system to trade/invest in stocks over a 3 to 12 month holding period.

I am interested in comments on the trailing stops people use once the trade has become positive. NOT the equity risk stop used at entry.

I guess I have a longer term approach which will look to hold the stock whilst it is in a long term uptrend.

The offset to this is how much profit is given away before the position is stopped out.

Any views out there?

Thanks in advance.
acturtle