What advice can you give me on verifying whether the prospects I am chasing for sales are actually the right kinds of clients for my business?
The easiest way to check is to look at your current sales and at the top customers, that is those that are spending the most money with you and are buying from you regularly.
Analyse them. Are you making a profit on their sales? If yes, then ask yourself what kind of customer are they? If your prospects are the same kind of customer then you are spot on.