Like most essential tools, it is better to have an up-to-date CV and not need it, than need it and not have it. Here's my advice on how to manage your CV.
The basics
First and foremost, get the flow and look right. Structure, spelling, grammar, and punctuation need to be perfect. A handy tip is to read all text aloud before you send in your CV. This quickly highlights any mistakes and areas that are clumsy and difficult to read. Although there is vigorous debate around the merits of a photo, I do not believe it makes any difference.
Keep your CV up-to-date
Treat your CV as a 'work in progress' document. An update every three months will only take 20 minutes, but trying (and failing) to remember which projects you ran two years ago will take a lot longer — and you risk underselling yourself. Order your work history with your most recent roles first.
CV length
Keep it concise. Focus on more recent roles and highlight skills and results that are relevant to the role you have been asked to apply for. CVs that follow a fad aren’t worth the risk. Stay conservative with a conventional format unless you are in a creative industry (e.g. digital, tech)
Make your CV relevant
A generic document that looks like it has been sent out in a hurry will lessen your chances of making it to the next round. Have a 'master' CV on hand with all your experience, but make sure any CV that is sent out has been tailored for the specific role you are looking at.
Expect due diligence
These days you can expect the highest degree of scrutiny when it comes to your track record and qualifications. If you have not finished a degree or certification, briefly explain why. The same goes for moving roles regularly. Expect questions and be prepared to answer honestly. A bad manager or poor cultural fit happens to us all.
Highlight responsibilities
As you move higher in your career you will need to quantify the responsibilities you have. Partly this is due to job title inflation (remember the days where the title Manager implied seniority), but also because moving into a new senior role carries risk for all sides. Use your CV to minimise the risk for the hiring company. For example, if you have a regional role, outline the countries under your remit, your headcount, budget, the organisational structure you worked under, and any other measurable responsibilities.
This is not intended to be an exhaustive guide — and there is no such thing as a perfect CV. Putting together a top CV is not hard, but neither is it easy, and you get back exactly what you put in.