If the author gives details of his/her website, then you can check it out.
If they have a website then ask yourself does it look professional? Are there any good (and genuine) testimonials? And significantly – is the website well-written?
Bear in mind that lots of career sector professionals, including many of those who advise others on CVs, do not even write their own CVs, but instead engage professional CV consultants to do the job properly for them. Just because someone puts an advisor’s hat on it doesn’t necessarily make them an expert in the subject. With many career sector ‘advisors’ all it frequently means is that once upon a time someone told them what they thought should/shouldn’t be included on a CV – many advisors therefore are merely messengers regurgitating the same old standard (and frequently flawed) information.
Surprisingly few ‘advisors’ have done any real research about what works best on CVs.
Whilst this may sound strange starting point, the first thing you really should do before writing your CV, is to stop and think.
And the first thing you need to think about is your target. Just what job are you targeting?
It helps if you can further sub categorise this – what level of job are you targeting? Is it a career change?
These are relevant questions because you need to adapt the way you write, depending upon the level and nature of your target. So hone in on your target and focus.