I include the 1st year and 2nd year prices for purchase, install, takedown, and storage as a total for each item such as c-9's, wreaths, garland, etc. I also include instructions on where these items go, such as south east corner to south west corner of home, or middle peak, etc. I may include more items than they buy, so I circle the ones they accept and x out the items they do not buy.
I mention that my contract renews automatically in "perpetuity" unless they fire me or I raise the price. I mention it is their duty to inform me they have moved. and I need to mention that their estate or heirs must inform me they have died. but a contract typically cannot go past death of the signee. But we have installed lights after someone passed and we had no clue.
I include my 48 hour service guarantee ( pending weather) mention we carry workman's comp and liability insurance, but also mention they should have approproiate home owners insurance. the reality is if any Christmas items get stolen from their house that they own while they are installed on their property, their homeowners policy has to cover that.
I mention how many years lights are covered under warranty, and what items are not covered, for us only theft and vandalism. I mention we stand behind our workmanship and some items ( like the transformers we sell for landscape lighting) may be further covered by a manufacturors warranty. I say if we damage their home in any way, we or our insurance will make it right.
Things I don't do - but - some folks do not cover weather related damage to lights and mention that in contracts. some folks also mention they do not cover or repair incidental damage to homes, like smushed shingles, gutter paint scuffs or general home scratches from ladders. and some make folks agree to mediation in the event of damage. I have also seen it go to the extreme of asking folks in the contract to agree to waive rights to sue to the contractor even in the event of negligence on the contractors part.
I have started including the need to call me and keep trying to speak to a live person when problems occur and we do not waive agreed prices if we are not informed of problems. Other wise folks will wait and tell you of problems in January when you try to collect from folks. You need a contract that states they have a duty to inform you directly of problems immediately as they occur. Your duty is to fix them.
It is really up to you how you word your contract. protect your self, it is your business, but be fair. The customer should have some rights too.