If you will be a subcontractor to a client doing say product development or construction, it is likely client will have a pro-forma contract for all such subs.
So you would take that to your legal provider (solicitor in Australia) for checking before signing.
If you want a "professional" looking shop front glossy document, that is not really on legal side although solicitor could check it too when finished.
You can also have terms of sale attached to your proposal. Usually the contract will include and over-ride that when contract is formed.
TOS templates probably available suitable to use, again get solicitor to check.
I used a firm of legal attorneys, and an accountant. overall their fees were reasonable , advice good, I always felt they were worthwhile.
By the way, are you in a state that is requiring registration? I was RPEQ beacuase a few years ago it looked like I would be doing design calculations and modelling for Queensland end user.