Of the three tips, I would say cleaning is the most important.
Clear off all surfaces for photos. That includes things like fruit bowls or spoon rests in a kitchen, remote controls or boxes of tissues in the living room, and miscellaneous supplies in the bathroom - no one needs to see your toothbrush. The one exception are well-maintained plants. Plants are a neutral to any space. As long as you aren't living in jungle, your plants can stay.
Clean those surfaces you just cleared and clean them again. Not just for photos, but the cleaner you have a home for when potential buyers come to look at it, the better the potential for a buyer to make an offer. It shows that you continually care for your home. Clutter and dirty surfaces make people psychologically stressed. Don't believe me? Take a look at this article from the NY Times: https://www.nytimes.com/2019/01/03/well/mind/clutter-stress-procrastination-psychology.html
One often forgotten spot to clean is your walls. Take a look at common touch points - stairwells, mudroom walls, and the bottoms of doors or near entrances. These spots can often have a buildup of oils from our hands or skid marks from our shoes. Take a tsp of powdered Tide and some hot water and wipe those surfaces down.
Schedule photos for both the right time of day, and the right time of year if you can. Monitor how the daylight flows through your house the best. Do you notice a certain time where the living room is flooded with light? That is when you'll want to schedule your photos to occur. A good photographer can brighten any photo - but having streams of natural light sources in a photo can really enhance the feel of the final pictures. Additionally, turn on every single light source you have in your home for the photo session.
Hire a real estate agent that you know uses a professional photographer to market your home. While a cell phone camera is okay, the professionals know exactly where to angle a photo, which light sources to emphasize, and can advise you on what you will need shift or move if need be. They can also bring additional light sources and potentially schedule photos at different times to capture different areas in different light if necessary.
Avoid taking photos with holiday decor inside - this can quickly make your photos look outdated or even potentially ostracize potential buyers from wanting to see it.
The nature of selling your home is that you want someone to buy it from you. The most important part of that is to allow potential buyers to picture themselves in your space. Decluttering really helps, but hiding distractions is often the hardest part because you live in your home and often go blind to the objects inside.
Top 5 Distractions:
1) Pets
2) Family photos
3) Children's toys and books
4) Religious Objects
5) Brightly colored objects that may not match the rest of the decor (looking at you t-shirt quilt circa 2003)
If you want to go above and beyond - hide anything that is not made of a natural material: plastic toys or cooking utensils or synthetic fabrics are the big two. Cottons, linens, metals and woods are all neutral and can stay if they don't correspond with the top 5 just listed.