PSA: Mages are in a much different spot now than they were in S4.

So if you aren't going to deviate from their S4 playstyle, do not play them! Save your teammates the grief! ** I'm only assuming they would grieve because I haven't seen a mage in the past hundred games! I'm looking to help out people start off on the right foot about playing as one this season. Of course champions with more kill potential are better in solo queue - solo queue is solo queue. But if you want to give a team more utility and some magic damage, mages are still the way to go.

Don't touch good S4 guides for them with a 10-foot pole. That S4 Ziggs guide on Lolking with 1000 likes that helped you get an 80% winrate last season? It won't keep you from getting mauled by assassins or bruisers in lane when you're inevitably forced to go all-in on them. They are designed to out-trade mages, especially now, and if you don't have sustain or movespeed they will out-poke you as well.

You could go for a utility role with most mages if you still want to play as them. In fact, the Utility tree isn't bad for them at all - it gives movespeed, CDR, bonus gold and some sustain, and helps solve mana issues as well. If you're still having mana problems then the Clarity summoner spell might help too - 40% of your mana back every 3 minutes can be a pretty big deal and teammates might appreciate the mana back as well.

Heck, your teammates might even appreciate a tanky CC-heavy mage like Galio - the Defense mastery tree might be good there.
TL;DR: whatever you do, don't try to out-burst people as a mage right now. That is certainly no longer their forte.