Guar Gum can be purchased here (this is an affiliate link): http://ebay.to/1IStyHZ
I decided for this video I would experiment with a Guar Gum based Giant Bubble recipe after many requests over the last year. It seems to work very well! On par at least with the J-Lube based recipe that I used in this video: https://youtu.be/VXsPqUFsArM
That is also the video to watch if you would like to learn how to make the giant bubble nets.
The best dish soap for bubbles is up for debate, but generally Dawn Platinum Power Clean is seen as one of the best. I also like Dawn's hypoalergenic dish soap which seems to work nearly as well and can be easier to find in stores. Anything labeled as a concentrate of '2x' is typically not very good.
Giant bubbles will work best in high humidity and in cool air, so mornings and late afternoons will give the best results. The middle of the night can also give great results, and the colors created in the bubbles by artificial lights are quite interesting as can be seen in this video: https://youtu.be/1sLu-TRYOeI