I use instant coffee and a Trangia to heat the water. Using water off the boil improves the taste compared to boiling water.
There is quite a difference in the quality of instant coffees. Standard Nescafe, Blend 37 and the fancy versions (eg Alta Rica) seem to be much better than Gold Blend or cheaper supermarket labels.
It is really hard to find small jars of good instant coffee in places where coffee=beans.

I like to make a large mug of coffee to wash down a bread roll from yesterday afternoon then pack up and get going ASAP.