I have a series of convex hulls that I want to overlay but I want to be able to see all of them at the same time. How do I do this so? I'm guessing making them slightly transparent will do the trick
If the polygons are all in the same layer/shapefile, transparency will be even more difficult to use. This is because layer transparency only affects between layers, not features on the same layer. There is a workaround where you create an attribute with a percentage transparency value and then you can have varying levels of transparency for features on the same layer - see my answer here: How to vary the transparency of symbols within a single layer in ArcMap?
Beyond just using outlines as suggested by the comments, your polygons don't have to have solid fills. You can use a pattern or marker fill as well - hatching at different angles, dots, a particular marker type for each polygon - circle for one, square for another, etc. This does require symbolizing your polygons on an attribute that keeps them all separate or unique and then setting up the symbol for each one.
Here's a simple hatch example from a quick exhibit I did recently where I needed to show two polys overlapped. It makes use of color, but you get the idea with the different hatch angles.