Although this show was fairly entertaining, it was a mess. Season 1 of Constantine had a lot of problems. Certain problems were very noticeable and led to a fairly underwhelming finale. Here are things that [Constantine](movie:874314) Season 2 should do right that Season 1 didn't. Spoiler warning of course.
Take The Side Characters Somewhere
A lot of characters in Season 1 felt shoehorned in. Jim Corrigan was only in two episodes, the first one was a decent introduction but when you never talk about him again and then shove him into the finale for the sake of him being in the finale, it feels out of place. Papa Midnite was in only 3 episodes and I really didn't know what the show was trying to do with this character. First he finds Constantine a nuisance, then he tolerates him enough to work with him and then he wants to kill him. You put Felix Faust in one episode which felt really forced as well. Take these characters somewhere, don't just throw them at a wall and hope they stick. Some people haven't read the comics and have no idea who these people are so show them who they are.
Develop The Villain Plot
What exactly happened here? In episode 1, all we know is that there is a rising darkness and a demon that has kidnapped a girl. I was assuming that they'd rescue the girl but they just seem to be showing how the characters deal with that incident. Lame. We don't actually find anything out remotely about the rising darkness until the mid-season finale when we find out that it was caused by a group called The Brujeria. We still don't know much about the group so we have to deal with that. The finale finally reveals that the Brujeria's leader is Manny the angel, a man who has not even been hinted towards being evil. I get it, it's surprising but at least foreshadow it a little so that it makes sense. And then you just leave us with that, we need something way more concrete. Don't keep us in the dark for any longer, we need answers.
Fix The Pacing Issue
The show's pacing felt so wrong and it didn't help that the season had been cut off to only have 13 episodes. 13?! Everything just felt odd. You replace the deuteragonist after one episode with someone who is missing every couple of episodes for "art lessons" and Chaz just seems to go on and off whenever he feels like it. He wasn't even in the finale. Make the season longer, keep the characters consistent, spread out the plot so it doesn't feel rushed. Simples.
That's what needs to be fixed on Constantine. This show can be really good as long as it fixes the problems it has. Otherwise it doesn't deserve a second season. Come on writers, get cracking. Chop chop!