Here are a few simple tips for how to take a group photo!

Pick a spot where your group can either be in front of a plain background, or far enough away from their background that it will fall out of focus in the picture.
Pro tip: If you can back up far away from your group and zoom in with your lens, that will make the background even more blurry and beautiful!

Try to be in open shade (that is, in the shade, but when the subjects look up there's nothing above their heads), or with the light coming from behind them - so that it's illuminating everyone evenly and not shining in their eyes, making them squint.
Pro tip: soft, reflected light is flattering, so if your subjects are facing (or close to) something large and neutral - such as a wall or sidewalk with the sun shining on it - that is an added bonus!

Everyone should stand in a straight line, not a U shape. People have a tendency to get into a semi circle but you want them to be on the same plane, to keep everyone in focus.
Get everyone to angle inwards slightly, towards the centre of the group (it's slimming and you can fit more people in).
Clean up the look by having folks do up the top button of their blazer, and put dangling hands in their pant pocket.
Pro tip: make sure people's chunky wallets, cell phones, lunch, or other random paraphernalia are taken out of their pockets, to avoid strange impressions in the trouser area.

"Happy Happy"
- The most successful prompt I've been using for years, I got from my friend Rudo Vacula, of Toronto Wedding Studios. It works 98% of the time: Happy happy!
- That's right, you - the photographer - say, "Okay everyone, looking right here," (or whatever you want for that part) and then you say, "HAPPY HAPPY!"
- It's amazing - it always makes people laugh.
"Mommy"
- In an emergency I have another one that I mostly use for groups including a surly teen or crotchety family member, and that is: "On the count of three, I want everyone to say the word 'MOMMY!' One, two, three..." and that totally works too.

"Look at each other"
- For a group of two I'll often take a few snaps, then get people to look at each other. I photograph that too, if they happen to have a nice moment together.
- The beauty is, after looking at each other, I get them to look at me again and take a few more photos, and this time their smiles are real.

Have fun practicing taking great group photos, with happy natural smiles!