Well, I would encourage you to put forth more energy and make a note to yourself before you start on the reflection or the breath again. Because if we allow the mental noting to totally dissolve and think that awareness of the hindrance is enough, it may be that the basic practice of mental noting, that helps you come to objective awareness, tends to disappear. Then we don't know whether we are using the reflection as a way to just get rid of the hindrance or push it away. So I would suggest that you bring up a little bit more effort, especially in the walking meditation and you are not doing reflections, to try to note these hindrances more, because it is very important to get to a certain amount of objectivity with our thoughts. Often times in the interviews people will say, "I can be aware of the walking. Is it ok to drop the noting?" I say for the body, if things are going well, it is ok at times, but I would like you to keep the mental noting of your thoughts, because it is very difficult to be objective with our thoughts as we have so much conditioning to identifying the thoughts as "me."
As far as having a special technique for remembering it, it is just a matter of trying to bring up awareness of the importance of it before you begin a session. Then make a resolution to yourself that you are going to try to note the hindrances. So making a resolution at the beginning of a particular period may be very helpful so that it is part of the focus of your meditation at that time. It may be difficult to do this at every period, but it may be very helpful at certain times to make a resolution that you are going to spend a little bit more effort towards bringing up mindfulness during this period. This little extra resolution at the beginning may help you to be more aware of the importance of it. Sometimes we find it difficult to do it because we don't understand its importance. So understanding its importance by making a resolution at the beginning of the period may help us to remember it.