There are several succulent specific groups on Facebook for the sole purpose of selling/buying that are free which eBay is NOT! Succulent Market Place and B.E.S.T I do some online selling and usually use Regular Priority boxes as opposed to Flat Rate because it is significantly cheaper. You may have to go online to the USPS and order the Regular boxes because they usually are not available at your local post office. The USPS has 3 different side boxes that have worked for me: 7"x7"x6", 12"x12"x8" and 7.5"x5.1"x14.4" (Shoebox). Boxes and shipping them to you is free. Next, find a source for discarded newspapers. Buy some wide cellophane tape. I, personally, like using mailing labels rather than hand written addresses and I do the postage online so I can just mail from home and don't have to travel to the post office all the time. There isn't a "correct way" to package plants. Anyone mailing plants has their own method that works for them and even this sometimes doesn't work out. I usually crunch up some paper in the bottom of the box, I wrap the bare root plant like you may have seen a butcher wrap a steak. place the bare root plant on the diagonal, roll it up a couple of times and fold in the sides and finish rolling. I used to tape the plants but no longer waste time or tape. Place in the box and crunch more paper on top. I hold the top closed and shake. If I don't hear any movement, I tape it. If there is movement, I add more crunched paper. The next most important item is a scale that generates weights in 0.2 oz increments. If you don't know the weight, you can't tell the buyer the total cost. Some people just use a flat mailing rate which may be more than the actual rate. I weigh EVERY parcel and ONLY collect the actual postage. I feel it is irresponsible and disrespectful to profit on postage.