I would use the smart guides.
But if you want guides that are always there, I'd use cinciamarotta's suggestion for Create Guides. What's cool about this method is you can divide the page into [EDIT] sixths, etc. at the same time.
Or you can create them manually by drawing a guide on the page and then, with it still selected enter the size of the page divided by 2 for the vertical and horizontal amounts.
For instance, for US Letter size page, you'd enter 8.5"/2 and 11"/2.
Thank you! Very helpful
Super! Thank you!
An easy question for most of you probably, but how do I set a guide at exactly half of my page, both horizontal and vertical? Google says View > New Guide and then add percentages to 50%. But in my indesign version (CC 9.0) there is no option for `new guide´ under the view menu.
You have the correct answers for InDesign.
Google was telling you about Photoshop, where you can find View > New Guide and type 50%.