We use a few different formats. Calls to action in buttons are always title case. These should be short (two to three words), action-oriented phrases. Avoid pronouns when possible.
Text with in-line links is another option. The hyperlinked copy can be longer than in buttons, and you should try to link a phrase rather than just one word. If it’s a link within body copy, capitalize and punctuate appropriately. If it’s an in-line link at the end of a section of body copy, use sentence case without end punctuation.
In Marketing, we also sometimes emphasize in-line link CTAs by having them on their own line after the rest of the copy — these are also formatted in sentence case without end punctuation, or with an arrow symbol.
Read more about how to write effective calls to action.