I've been doing daily mindfulness in very, very small doses for 6 or 7 months, but as a compliment to my daily meditation practice. I've always meant to be more diligent about it, but I just never was. About 4 or 5 weeks ago I became interested in lucid dreaming. No LDs yet but I've really been working dream recall and doing some RC work. I was vacillating back and forth between which daily awareness work felt right for me. SAT, ADA, Dream Yoga, etc... So about a week ago I decided to try this approach to ADA. As I said in my above post, it's really what I was intending to do, more or less, in conjunction with my formal meditation practice. Lucid dreaming gave me the incentive to take it to the next level. :-)
My thought on this is along the same lines, and I'm thinking putting particular focus on the interoceptive aspect is particularly helpful as that is the common denominator to how we relate to all experience, both external and internal. The act of gathering information through the senses builds up a database of experience that shapes our expectations, but the more personal and intense aspect is how we react emotionally, especially if something is outside of the ordinary realm of experience and expectation.
EDIT: One other thought...
Choosing one particular thing to be aware of throughout the day can act as an anchor for awareness. I know how difficult it is to practice being mindful of the routine things we do throughout the day. Eating, dressing, brushing teeth, etc... They are all discreet events that are done and over in relatively quick order, and for myself I often find so is mindfulness.
However having one thing like gravity or breath or something else that is ever-present can keep us more mindful of being mindful for much longer periods of time. I also find when I am being mindful of one thing, I can be mindful of anything else that requires my attention. I think the trick is to pick something that an individual normally has a strong sense of awareness for. For instance you mentioned the sensation of your clothes is more present in your Now than gravity.