How to best play Demonology in PvP?

I'm a filthy casul, but I like playing the summoner spec in PvP for autistic class fantasy reasons. What would your recommendations be to a relatively new Demo lock playing arenas with randos?

I've liked playing with IMPending Doom because more demons and more shards, but I'm hesitant to couple it with hand of Guldan outside of PvE simply because I like power trip a lot more with SI, Empower > SBolt spam is a lot harder to kick and leaves me a tad more mobile, and lets me burst harder. Maybe I should be taking Shadowflame like everyone recommends even if I can't easily keep the DoT ticking properly? Also, I'm a firm believer that Darkglare is deceptively useless, seeing as how he's slow and gets LoS'd easily, and is kind of only good when he's able to get solid spread pressure.