Legally covering every aspect of my Tech Repair Business

So far I haven't gotten too far in this area. I've copied and pasted some legal forms and made it applicable to my company but you have to pay to have them signed. I also added some disclaimers on my website. I still need to produce a general contract for services, invoices, and all other legal documents I might need. I'm not sure what all legal documents I might need.

I know when you're working with customer's computers you have to produce a contract to release liability in case of damages. I'm not sure what other liabilities might come up.