A lot of good advice here by experienced folks on this site; they're so helpful and compassionate! I've been living with my ileostomy since Thanksgiving last year, and I've come a long way since I got out of the hospital! One thing I learned from them and from personal experience is that everybody is different and unique, so what works for one may not work for you. But try the different products until you find one that works for you, then stick with it until you need to change again for whatever reason.
I definitely had leakage issues if I didn't use a barrier ring. I've had the best luck with Hollister Adapt Rings; for some reason, the other brands didn't work as well for me. I also use an adhesive remover during my changes (non-alcoholic ones designed for peristomal skin). That makes removal less damaging to the skin and helps remove the ring if it's still being sticky. I found that if my cutout was too large (you have to be sure your cutout is as close as possible around your stoma without impeding it), or I didn't place the wafer around my stoma "just right," the fluid output would make the skin around my stoma itchy during output. Stoma powder and Cavilon barrier spray work great for me (don't let your supplier substitute with some no-name brand; Cavilon is the gold standard. Use a different vendor if they won't give it to you; I had to for this reason). Coloplast's barrier spray is also acceptable, but Cavilon is the best (for me) IMO.
Work with an ostomy nurse if you have access to one. They've been great for me and have access to all different types of products you can look at and then ask for samples to try (from the vendors, all of whom are great at providing samples to try).
Ileostomy stomas will always have more liquid output, thus are more prone to leakage because the liquid will eat away at the barrier seal, and you have to find the balance of food, meds, and ostomy products that work for you. I have a partially flush stoma that barely sticks out above my skin on one side and is flush on the other half, so I have to use a convex bag (Coloplast light convex, 2-piece) with a barrier ring (Adapt) to get a good seal, along with stoma powder (I found any brand seems to work for me) and barrier spray (Cavilon) to make it all work together, in addition to food changes and taking loperamide. Let me tell you, it was a process to figure all these combinations out! Good luck!