I have some potential clients that ask to see something before accept the work.
Now, should I make, for example, a free mockup or It’s better to find another client?
Answer
That sounds like Spec-Work.
You should show them what you are capable of (i.e. your portfolio) but be wary about doing any work for them for free.
Attribution
Source : Link , Question Author : Alex , Answer Author : Iain Holder