I've decaled only one EF team so far, but they turned out pretty well. I've been a model builder for 40+ years so I have LOTS of experience with waterslide decals. There are a couple issues one has to watch out for with waterslide decals. The first is the thickness of the decal. Some are very thin and some are thick. The thin ones settle into curvesand corners nicely, but can be delicate to work with. Thicker decals are easier to work with, but don't like settling into curves - which brings me to the second issue - decal setting solution. Most videos you see on decaling EF teams talk about using a decal setting solution. What decal setting solution does is soften the decal so it bends easier and adheres to curves, bands, etc. It comes in varying strengths so you have to gauge it to the thickness of the decals you have. If it's very strong and your decals are thin and fragile, the setting solution can turn your decal into a bunch of goo. With the team I decaled recently I started out using Solvaset as my setting solution, but it turned my first decal into mush, so I then switched to Micro-Set and that worked a lot better.
The process of decaling is fairly simple. Make sure the surface you're applying the decal to is clean and smooth. Cut out the decal as close to the edge of the visible portion of the decal (i.e. cut off as much clear film as possible) as possible, place it in water for a few seconds (the time you want to keep it in the water can vary depending on the decal brand) , then once the decal slides off the backing paper, slide it onto the figure and position it. Make sure to keep the surface of the figure slightly damp as that makes it easier to move the decal around. Once you're happy with the placement use a paper towel to soak up any excess water. Make sure to press out any air/water bubbles that are under the decal to make sure it is sitting properly on the figure. Apply a small amount of decal setting solution (I use a small paint brush) and if everything looks good, leave it alone until it dries. After it dries come back to make sure the decal is completely adhered to the figure. Sometimes edges won't adhere so if that's the case wet that part of the decal with setting solution, press it down, and let it dry again. Once you're happy with your decal job, apply a coat of gloss glaze (I use something I bought at Michaels called Dura Clear High Gloss) over the surface of the figure to seal and protect the decal and you're done.
One thing to do is before you start try practicing using a decal from the same sheet you're going use that you don't mind messing up. That way you can perfect your process before you start using decals that you might not be able to replace.
I hope this helps.