Here is my methodology, most of which is found in Reichmann's
excellent book.

1. Develop testable 3-D models of the lift in your mind, based on
topography, wind, sun aspect and previous experience. This is my
version of "strolling along the ground to find where it is hot" in
Reichmann's definitive text.

2. Test the model by putting the glider in what you hypothesize as
the best energy lines.

3. Fly as precisely and efficiently as you can and in an direct
correlation to the intensity of lift/sink/turbulence: Smooth and easy
inputs in light, smooth lift. Firm and aggressive when it is rock-and
rolling. The flight paths of world-class pilots can appear as though
they are drunk or very sloppy as they weave about. This is in direct
opposition to wings lifting and can be used to locate in featureless,
cloudless terrain.

3. Adjust your mental image and flight path based on test results and
observation of other ships, birds, dust, etc. I believe AJ Smith and/
or Dick Schreder said that 90% of what you need to know is outside
the cockpit and if you have not made a decision in the last 5 minutes,
you are not working hard enough. Electron Slingers allow you to
direct your attention and energy where it matters: OUTSIDE THE
COCKPIT. A glance at the moving map periodically is all that is
required to affirm your location and that you have suitable fields in
a reasonable glide, how you are doing on task and what you need for
final glide.

3. Repeat this decision-action loop every 1/2 hour or so based on
changing wind direction and intensity, sun aspect, and terrain and
what is 20-50 miles down the road.

I would also echo what others have said:

When close to clouds, use them as the primary reference. And not just
"sort of under a cloud". You need to determine which side of the
cloud and what cloud phase is optimal and what height below base.
Target and test the clouds you select and adjust your selection
process. As one gets lower, lift hunting is more and more attached to
the terrain + wind + sun aspect.

Finally, be mentally Tough and never quit "soaring" until you commit
to landing. As someone said previously, many flights have been
"sucked off the ground", mostly due to the pilot's persistence and
willingness to fight until a safe landing is inevitably necessary.
"Giving up" is very seductive and absolutely ensures you will land.
Both of these behaviors are self-reinforcing; both become easier with
repetition. "Grinding it out" is where our hang glider brothers
really excel.

The paradoxical situation we find ourselves in when low and facing an
off-field landing is one of the many things I find interesting in X-C
soaring. Just when we are under maximum stress and with minimal
options, we need to be at our absolute technical best and most
creative. Gotta love it!