I'm not at this level however another poster that does a lot of up scale work gave this advice he always goes and pays a visit and walks the property with the customer for free.
It gives him the info to determine what the client wants, and knowing the lay off the land gives him further knowledge to figure what will work at that location.
More important it gives him the chance to sell himself and his business, instill confidence in him with the potential client. For it's not always price that gets the job.
This 1/2 hour to 1 hour meet and greet ends with learning the amount the client wants to spend, any plant type preference.
The client is then told off the top of his head what can be done for that amount and at this point designs must be drawn up with plants specifications and any hardscape work. That it will cost x dollars for the design stage if the client wants to go forward at this point.
Take it from me, CHARGE CHARGE CHARGE. It is important to come up with some guidelines for your designing fees. this is what i do
first 1hr meeting FREE
Design contract Min. $ 250.00 (half up front)
A typical design for me is 1. existing site
I issue all designs on 8.5 x 11 paper for 1/2acre and down, 24 x 36 for larger
This will usally take me about 3-4 hr. ( $350 to $450 )
1/2 hr review with customer FREE
additional review and modification $80.00 per hour
Inspection fee of $150.00 if you are not contractor.
All customers are different adjust price accordingly. I will always want to do the work, so offer discounts on designing if I do the work.
Always get a contract signed, no matter what size the job.
I do about 80 to 100 designs a year, with an install rate of about 90%
I would always charge to design something otherwise the customer would be able to do it themselves of have someone else do it for cheaper. And you get paid for the time it took you to come up with the design.