I found that the best way of dealing with these questionnaires was initially to identify whether you could do the skill or not.
If I previously had carried out the skill in my experience and knew I could do it I would place it in the middle, rating 3.
Any skills I was not sure about or knew I definitely could not do them I rated as either 1 or 2, the lower ratings. Then I would review the skills and upgrade those I thought that I am particularly good at to 4 or 5, the highest ratings.
NB: I rated my word processing skills as 4, despite not being able to numbers onto word documents, because I considered that I have a good working
knowledge of Word, and can execute most other tasks. Otherwise, it is possible to underrate your skills