Kitchen design bids and contracts. Question for designers or contractors.?

Question:If you're a kitchen designer or contractor:

I've been a kicthen / bath designer for 4 years and have never quite mastered the skill of writing contracts / bids for my clients. They always seem to find crazy loopholes in my proposals to get free services and products at the end of the job.

The company I work for doesn't have a standard contract for clients to sign - I'm looking to see if anyone out there has an airtight format they use.

Answers:
I used to run into this problem too. During the years that I did kitchen and bath remodels, I used a standard home improvement contract that had all of the required verbiage for California law...but most importantly I added a second page that spelled out item by item what was included in the bid and a second column that spelled out what was NOT included in the bid. In other words "I will install new cabinets of so and so design and quality but I'm not going to repipe your house for this amount of money" Also, its important to have the prospect read and sign this addendum and have a clause that spells out that change orders must be in writing and always result in extra cost such as actual cost of time and materials plus a reasonable profit. Seems like people will always try to chisel a little here and there and its important for them to understand that this is this a business and everything costs.