Trap 1: general quotation of confusing materials
Trap 2: the terms are not selfish.
Trap 3: Underreporting the workload will make you happy.
Trap 4: Stealing materials to earn the difference.
Trap 5: The quality of the same material varies greatly.
Trap 6: Cut corners and cheat the homeowner.
Trap 7: confuse the concept and charge more.
Trap 8: Pay in advance to save your life and ask for money.