This is a really important exercise to undertake. Your perfect customer ideally is already your most profitable 'best customer'(s), but it might not be...
So make a list — what are all the attributes of your perfect customer?
What are your perfect customer's likes and dislikes?What is your perfect customer's budget?
How does your perfect customer define 'Value for Money'?
What level of service does your perfect customer expect?
How often does your perfect customer buy the product or service you sell?
How does your perfect customer use your product or service?
Where else/who else do your perfect customers buy from?
How do your perfect customers like buy?
If consumers: what ‘demographic’ are your perfect customers? (age, interests, family status etc)
If businesses: what 'vertical', 'size' or 'type' of business are your ideal customers?
What other things does your perfect customer spend their budget on (this is a very relevant question, as it identifies competition for you. Remember your competition might not be an alternative supplier of what you sell, but something else your customers spend money on)
With the answers to these questions you can now see if your perfect customer 'looks like' your current customers.
If they do — great! You know what to do now — get marketing to find more of them!
If they don't, then you need to make a decision: can you package your existing products and services to appeal to your perfect customer(s)? Or do you need to find something new to sell them?
Your perfect customers exist — you just need to have what they want, and tell them about it.