The most helpful things your dog should know how to do are 1) look at you with attention and 2) sit.
The easiest way to get your dog’s attention, if they do not look at you by name alone, is to hold a treat. Using a treat as a lure will also help you guide the direction your dog is looking for your photo, such as straight at your camera. I hold my phone in one hand and a treat in the other a few inches above my phone. Play around with the distance and angle needed to get the right photo. There are also clips and attachments for your phone that you can use to hold the treat for you.
My favorite treats for any training are Zuke’s Mini Naturals. These treats and dog food are the only items I have on Amazon subscription. They are unfortunately in short supply right now since the brand voluntarily pulled all stock from sale due to a quality control concern. I prefer the peanut butter flavor – my dogs like all of them, but the meat and particularly salmon flavors can come back to haunt you in doggy breath later. In the interim I have been using these Buckley Trainers treats recently and they are very similar but a little larger than Zuke’s, so I’ll sometimes break them in half. For budget-friendly treats, consider making your own, using your dog’s regular food, or small pieces of pet-friendly food like carrots.
If you need your dog looking another direction, are going to be more than a couple feet away, or using a professional (two hands) camera, recruit a second person to help you. They can hold treats or toys up leaving you or the photographer to focus on just taking photos. My friend Erin can capture the dogs’ attention without even necessarily holding out treats!
A good sit is also important for photos. I find it to be the easiest pose to keep your dog still and be able to move their gaze around. If they have any costumes or clothing on, this also provides a good front view of the outfit or keeping anything like a hat steady (generally, you will need a hat with straps or ear holes to secure it). If your dog can hold a down stay, that is also a good pose for photos.
With two dogs, my biggest challenge is usually getting them close enough together and then looking the same direction. At close range, I nudge them dogs together or lure them into position with treats. Again, a second person maybe helpful to get them both looking the right way. I also find indoors or full shade to provide the best lighting. You can take photos in sun, but will need to be mindful of where any shadows fall, especially if you have your arms extended to hold your camera or treats.
If I am outside in an open area, I’ll usually keep the dogs on leash if I am taking pictures by myself. Tucker is prone to distractions and might startle and bolt if say, a scary plastic bag blows past in the wind. Outdoors, I will lay their leashes down out of the way and step on one or both. You can also tie the leashes to something like a tree if convenient. For photos specifically, a regular clip-on leash on a flat collar is easiest to hide and maneuver for photos versus a harness. I also have extra long training leashes that are great for more space taking photos.
If your dogs make too serious a face for a treat (above left), try walking them around or have them trot to you with the come command so they drop their mouths back open or pant. This will look like a smile in a photo. The caveat is if you try this after a long walk or when they are too distracted, their tongues and faces might go too far the other way to hold a nice pose.
Most importantly, be patient and practice! Even if your pet is doing everything perfectly, they might just blink in a picture. For every good dog photo I have, there are 5-10 not so good versions. Keep it fun for yourself and your pet so you can continue to take more photos!