You will need: Green yarn, red yarn
I'd be more specific as to yarn type, but I used local materials found here in Ethiopia and my options of yarn type is only one. And it's made of plant material instead of wool. It's very thin, and as such I used a 4mm hook for the wreath and a 00 for the berries and bow. You'll have to choose your hooks based on what material you decide to use and your tension, I tend to hook loose.
Using your green yarn, chain stitch 10. Single stitch into the chain row, and then you can start adding height. I used the triple stitch, it enabled me to get a lot of height on each row and thus complete a wreath in about an hour. A good thing when you're making a bunch to mail out as Christmas gifts. However, more textured stitchs like puff or bobble would work well too and would be a good choice if you aren't making these with a close deadline.
At the least, you'll want the length to be as long as your forearm. Even if you decide to do a larger wreath, I'd recommend still using a width of 10.
Once you have your strip of 'evergreen' croqueted out, arrange it in a circle. It should fold at least three times, if not make it longer. Slip stitch the ends together, pull tight, and trim the ends.
Tada! You have a wreath.
The bow is just a really long chain stitch, sixty to be percise, but it's best to not chain it all at once.
Chain ten, mark it with your thumb, and then chain twenty more. Slip stitch into the tenth look, where
I tried a couple ways of making them; attaching small balls balls, multiple single stitches in the same place. What I found best was a single puff stitch followed by a chain stitch. It laied pretty flat and didn't result in random ends showing.
Optional finishing touches:
You can use clear nail polish to make sure your berries don't come undone and use it as glue to keep your bow's loops in place. It's also possible to sew on small Christmas charms you can find at craft stores in the States.