We recently finished a series of four shooting courses here at Light and there is one piece of gear that is consistently needed. Regardless of subject, technique, camera, etc. the HoodLoupe is a must have.
I did a video last summer regarding the HL (HoodLoupe Video) and every shooting session reconfirms.
There is such critical information available to us on the LCD whether in Live View before the shot or when reviewing images/histograms after the shot; try not to pass it up. The loupe will help you eliminate distractions and overcome bright lighting conditions to focus on the LCD.
As you know, I am always a full disclosure guy. Hoodman does not compensate me for endorsing their gear. It is just the best stuff out there.
If you do not have one yet, just do it.