I survey otters and it doesn't quite work how people think.
Forget about being quiet and try to spot an otter - you won't unless you're mega lucky - you're not looking for the animal, you're looking for the sign, not old sign or recent but FRESH sign i.e. the last 24hours - being able to age the sign is important. The aim is to cover as much ground as possible in the same day not to sit in one spot. You will need a car as one otter could patrol 10 - 15 miles of river and stream and you'll need to travel to various sites in one day.
Survey sites should be allocated to each member, it helps if they know the area.
The survey MUST be carried out by everybody on the SAME day, there's no point one person recording a fresh spraint on a Friday and someone else recording one 5 miles away on a Sunday. This is how numbers can be exaggerated, instead of recording 2 otters, chances are it's the same otter.
Sign can be found some way from the waters edge don't have your head down all the time.
Look for spraint sites and anal jelly - logs, rocks, man made features, castling - raked up foliage and earth to create a mound on which to spraint if there's barren land. Spraint will always be your main indicator.
Just because there's no spraint doesn't mean there's no otter, a female doesn't advertise so much when in cub.
Also look for tracks, feeding sign, slides, possible holt sites, runs across land (perhaps to negotiate a weir), evidence of rolling in grass to dry off. Also note mink activity and presence of water voles whilst your out and any description of the water - high, low, polluted, site inaccessable.
You should be given a record sheet to fill out with OS coordinates of each site and the otter sign that you found. Record everything but make sure you age it - Fresh (F), Recent (R), Old (O), Anal Jelly (AJ).
Prints should be photographed with a sense of scale in case there are juveniles.
That's all I can think off the top of my head at the moment.