Before you buy any new domains its always best to make sure you have the main ones first like .com, .net, org and your country TLD plus any TLDs of the countries you target. You can buy new TLDs related to your business, interest and niche.
You can also buy TLDs for specific countries like .london and .newyork so you can target specific cities.
It’s also good to protect yourself if you are running a company, perhaps mainly if customers may get upset. You may have to look at negative TLDs so an upset client doesn’t get to it before you do. Examples could be .boo, .sucks and .wtf etc.
Acceptance for these new TLDs is a slow process for public and start with not many people other than those in the industry will no they even exist. Also some browsers that users will use do not recognise the new TLDs just yet and will often browsers will attempt to search them in search engines instead of the correct link.