I had so many leaks for the first couple of months, frustrating isn't a strong enough word. My stoma changed gradually from being round and sticking out about an inch from my belly to becoming more oval and flat, like it was sitting in a divot. I tried many products but finally settled on a moldable convex wafer and stoma paste from Convatec. I use the paste instead of rings because it's easier for me to get the paste to fill the gaps around my stoma caused by the way my belly folds.
It took a visit with an ostomy nurse recommended by my surgeon and samples from Hollister, Coloplast and Convatec. I learned very quickly that all the supply companies are more than willing to send samples, have you speak to their ostomy nurses and they usually follow up to see how things are going. It was a bit of trial and error but I found what worked. For instance the Hollister wafer was ok but the Convatec convex seemed to adhere and work with the stoma paste better. I also found I really liked the Coloplast pouch design but their wafer was an issue for me (my stoma is very close to my belly button and their design doesn't work well with my folds. Again it was a lot of trial and error but once I settled on the convex wafer and paste I have had zero leaks. The use of powder then the application of the paste has really kept skin irritation to a minimum.