Suggestions for conducting a Website Audit

Hello Sitepoint!
I’ve been contracted to perform a website audit for a client; I’ve done a thousand of them (internally) as part of my discovery process with clients prior to building them sites - but this is the first time I’ve been asked exclusively for a Website Audit.

Does anybody have any general suggestions on how to proceed? The audit will mainly focus on how their existing website empowers (or fails to) their brand, UX/UI, Info Arch, and overall aesthetics.

Have any of you provided a website audit before? Care to share your experiences?

Thanks!!