Make sure you are knowledgeable about sidings, especially the installation process and maintenance. I've seen far too many bad installs and improper maintenance.
The worst installs were vinyl sidings. I've to strip too many of them when the underlayment was rotted to the point it had to be replaced.
The best install I've seen was from BensonWood. See this link if you want the details.
https://nakamotoforestry.com/wp-cont...ing-Manual.pdf
It may be extreme but it's a great guideline to go with when designing a statement of work with an installer.