My first 5man group was a priest and 4 mages. Its easy sauce to setup. You need like 2 macros. One for AOE and one for single target (bosses etc)

AOE is easy to set up. Just put arcane explosion and Holy Nova on the same hotkey and your set. (you will want to glyph holy nova eventually after the circle of healing changes)

For single target I just left it blank for my priest but for my mages I had the following. You will need to adjust according to your level and how you spec.

/assist priest
/use 13
/use 14
/cast Presence of Mind
/cast Arcane Power
/cast sequence arcane barrage, arcane blast

Now I haven't used this group in prolly 5+ months and I know there have been some changes with PoM and Arcane Power so im not sure this macro works like it did. I had a few more set up with pyroblasts, and rotateing slows etc, but thoes two I used 95% of the time with my priest and mage group.