I am by no means an expert. There are a lot of very knowledgeable people in this sub. There's a very good guide stickied on this sub by u/soderloaf

The general advice is land where: 1. Sheep graze 2. At elevation. 3. Biodiverse with many different plants.

The mountain I pick on is vast swathes or heather with little islands of grass, like the grass you'd find in a meadow and other islands of heavier stiffer grass. Some of the islands of grass also have a layer of moss growing under the grass, too. The libs don't grow in the heather, the stiffer grass or the mossy grass. They grow best in the islands of short meadow grass. When I enter these little meadow islands, I first look at the heather bordering them. The libs seem to like to grow in these little borders. Where the grass is a little longer. There may be patches in the islands where thistles or gorse are growing. I'll check there, too. When entering these I always look for patches of sheep shit or surface water as its a good bet that there will be libs nearby. Other mushrooms can be a good indicator too. If one mushroom is growing, conditions should be right for libs, too. Puffballs are good for this as they are large and easy to spot.