Taking the car out of gear (except to change gear obviously) while you are driving is not a good plan.

This is called "coasting", and if you do it during a driving test in the UK, it will count as a fault (IIRC). This includes both putting the car into neutral or travelling with the clutch pushed in, unless actually changing gear.

A book I have here, "The Driving Manual" (published by HMSO) lists all the reasons that Andy gives as to why coasting is a bad idea.

I also use a combination of engine braking and brakes. I use less engine braking on my new car, because it just doesn't seem as effective (relatively high-revving petrol vs diesel).

I never change into neutral unless I've stopped the car and am getting out, or unless I'm stopped at lights for a long time, in which case I'll put the handbrake on as well. Normally I just push the clutch in as I come to a stop, and put the car in first, ready to go again.