Intellectual property is the set of rights over things a business creates or uses to identify itself.
The kinds that matter to a service business
Trademark — the business name, logo and any slogan. This is the one with real value for a trade business, because reputation attaches to the name.
Registering a business name is not a trademark — see business name registration. Rights can arise from use, and registration makes them far easier to enforce.
Copyright — written and visual material: photographs, site copy, drawings, manuals. It arises automatically on creation, and belongs to whoever created it unless agreed otherwise.
Trade secrets — pricing method, customer lists, processes. Protected by keeping them confidential rather than by registering anything, which is why confidentiality terms matter — see restrictive covenants.
Patents — rare and expensive for a service business, relevant only where something genuinely novel has been invented.
Who owns work that was paid for
Not automatically the payer. A contractor who designs a logo or writes copy generally owns it unless the agreement transfers it.
Businesses routinely discover years later that they do not own their own logo. The fix is a written assignment at the time, and it costs nothing then — see customer contracts.
The same applies in reverse to anything the business creates for a customer.
Photographs of work
Useful marketing material, and worth being clear about: who took them, and whether the customer consented to their property appearing.
What to actually do
Check the name is free before committing to signage and vehicles. Register the trademark if the name matters. Get written assignment for anything designed or written for the business. Keep genuinely confidential things confidential.
Beyond that, most intellectual property spending is not warranted for a local service business.