I would paint the side door the same color as your siding.

Although your front entry walkway is charming, it also feels less "official" than a true main entry walk. I would pour a more substantial walk to the front entry, bringing it more attention.

Is there an obvious path from the driveway past the side door to the front door?

Why are your house numbers AND your mail box at your laundry room? You are drawing people to that door with those items. Move them to the front door. Downplay the lighting at that side entrance, too.

threers - No there is not an obvious path from the driveway past the side door to the front door-- but that would be a good idea.

Would you consider closing up the side entrance? Can you enter those areas through the garage? And yes to ptreckel's points!

Simple solutions also work best. Can you put a cute sign up on the side door that says "Please use the red front door. Thank you!" with an arrow pointing that direction? No need to reinvent the wheel, though you can try some of the other suggestions as well.

Add some splash to the entrance you’d like to emphasize with large ceramic planters filled with greens and flowers. Paint that front door the same color as the planters. Draw your visitors to that space. Paint the other door the same color as the house and replace the address numbers there with a small sign that says please use main door. :-)

This is confusing! You are saying you want to hide the SIDE entrance but is that the one in the MIDDLE of the house as you look at it from the outside? In any event, you’ve got some great suggestions here although some might be reversed.

Put a gate on that walled entry and a sign. Many houses here have signs about using a different door or how to leave packages that are permanent.

Others have made great suggestions, especially about making a clear path to the door from the driveway and street, and adding other visual cues like moving the mailbox, cleaning up the landscape, etc.

You could also stage the mudroom entry area to define it as a private courtyard so people keep walking past it. Beams across the top so it looks like an outdoor room, furniture positioned to semi-block the path to the door (like a round coffee table in the middle of a seating group,) a large outdoor area rug, plants, etc. A waist high gate will cause visitors to stop before entering and look for the other cues leading to the front door.

Move your mail box to the entrance with the red door.

Adding a cute little wooden gate to the “side” entrance would be great. And you could even place a small arrow on it with the word “Entrance” on it to guide visitors to the front door.