Maybe the best way is to get moe work than you can handle, and then you won't need T/C, because if any custy starts to cause you stress, you drop them.
I've found the answer to most problems in this game is get more custies.
I agree with Cozy - trying to impose conditions on the customers is a dead-end street, they'll just tell you to do one.
We use T&C's but only to establish what we will/will not do and under what conditions:
TERMS & CONDITIONS
1. WEATHER. We work in most conditions, but see the
RAIN GUARANTEE in the attached leaflet
2 APPOINTMENTS; Only by special agreement - substantial
additional payment required.
3. METHOD: See "Water Fed Pole" leaflet
4. PERIOD: Every 4 to 6 weeks, depending on work load
never less than 4.
5. HOURS; 8.00am to 6.00pm Monday to Saturday
6. ACCESS: Required at any reasonable time ONLY for
performing service. Fully insured, copy certificate
supplied on request