I just used SD formatter, then used win32diskimager to write the SD image then used raspiconfig to expand it to use all of the space.
The guide works for 3.0 as well. Most configurations can be done from the new retropie menu in emulation station. I have 3 or 4 microsd cards- I use smaller ones for testing and have a 64 GB one for my main setup. It was good for me to have a few because I corrupted one beyond repair. They are relatively cheap from Amazon.