Your brand, your product name, your slogan, logo, even the shape of a perfume bottle or a stripe on a shoe!
A Trade Mark should be Non-descriptive
Apple for a shop selling apples would not really work but it does with electronic products.
A Trade Mark needs to be distinctive
“Great holidays” might sound like a good idea as it explains your services but it does not allow customers to distinguish your brand.
You need to choose classes
There are 45 different classes of goods & services. Official fees depend on the number of classes you pick up for your registration. Think at least 5 years in advance, you cannot add anything to the application once filed.
Is your Trade Mark available?
The worst idea is to pick a name that is already registered or being used by another business in the same field of business (class).