Should I secure all verions (TLDs) for my domain name?
Where possible; "yes" would be our recommendation.
eg, let's say you have a company called "My Lovely Company" and you have the domain name www.mylovelycompany.com
If a competitor came along and bought the .co.uk version; eg www.mylovelycompany.co.uk or the .net version; www.mylovelycompany.net then that could be bad for your business for a number of reasons:-
a) People often accidentally type in the wrong part of the last domain name (getting confused with .com / .co.uk) meaning they could go to your competitors website
b) Anyone going to the wrong website means lost sales and a poor reflection on your brand
c) It also makes you harder to reach by email if you have email on your domain name
Whilst there is a cost for securing multiple versions of your domain name, this can be a minimal cost compared to buying the domain name from a competitor or somebody who has merely decided to buy it for the sake of putting up a porn or scam website. So yes, buy each version you can reasonably afford!