I guess the most common problem I run into with a risp
is having immediate expectations of my students that are too high.
This delicate balance between believing your students can achieve great things in mathematics one day,
and knowing what it is realistic to expect of them in this particular lesson on this particular day
is well expressed in the quotation below.

The most important feature of a task is that it contains some challenge without being overly taxing.
That is, it does not appear to be trivial, nor does it appear to be beyond the learners' capabilities.
Tasks which demonstrate to learners that they are capable of more than they can imagine can do wonders for building their confidence;
on the other hand, tasks that have been 'suitably simplified' to be well within the learners' capabilities
are likely to be seen by them as not worthwhile, and so may demotivate rather than inspire.
A great deal depends on the atmosphere of trust between the learners and the teacher.

John Mason and Sue Johnston-Wilder, Designing and Using Mathematical Tasks, Open University, 2004

In my experience, students are far more often likely to complain a task has been too hard than too easy!