Wave bars are usually only 3-4 nms apart. If you can't see the ground then try to imagine what feature is likely to be setting off the wave (assuming that you know your present position and the forecast wind).
Turn downwind for a couple of minutes and watch your ASI and VSI very closely. As soon as you start detecting an increase in speed and/or lift, resume your original track.
If it is not possible to fly parallel to the wave bar, then try flying a series of small doglegs. I have made considerable fuel savings making use of wave. I once saved 4000 lbs of fuel in an Argosy flying from Tehran to Cyprus and I have had a Belfast flying at cruise speed with the throttles at flight idle over the Massif in France.
I would have to say that my experience in wave soaring in gliders in such places as Dishforth, Sutton Bank and Aboyne comes in very handy. You don't have to have dramatic mountains to create wave and it can exist a long way downwind of the feature that is causing it.
I can remember someone getting to 17000 feet in Oxfordshire in weak wave created by the Welsh mountains.