I normally advise new bird watchers to take no notice of a birds common name when trying to identify a new species. For example, you never find garden warblers in gardens and willow warblers can be seen in trees other than Willows. For pipits, however, with other factors taken in to account, it works. There are eight pipits seen in Dorset and of these, four are very uncommon you are unlikely to see Richard's, tawny, olive-backed or red-throated - leave those to the experts! That leaves four to choose from.
The water pipit is an occasional winter visitor to watercress beds on Dorset's rivers so if you see a pipit away from this habitat it almost certainly won't be a water pipit although they also turn up around reed beds, especially Lodmoor and Christchurch harbour. Tree pipits are found on our heaths, usually perched in the occasional birch or pine trees that occur there. They are also summer visitors and easy to match up when you find one thanks to the heath/tree connection. The rock pipit is a Dorset resident all along our rocky sea cliffs and ONLY on our rocky sea cliffs, hence rock pipit.
This leaves the meadow pipit (Anthus pratensis) for everywhere else! Heath, downland, rough pasture, even farmland are its preferred habitats with a marked drift towards coastal regions in autumn and winter. It is also our most common pipit sometimes appearing in quite large flocks. The one in my hpotograpph is a little one (probably not quite an adult because it is still very light underneath) is not by a watercress bed, not in a tree on heathland, and not on rocks, it is on coastal downland and so its a meadow pipit!