If you don't have a good understanding of each map, their objectives, the enemies that will spawn, how they work, basics of CQC, and a general idea of how to be an antagonist, then start off learning those. Specifically, make sure you understand how the ai works.

Being a 5th council character, she has a slow movement speed, armor, slightly weaker CQC, and a weapon with no reload. Her ability allows her to deploy a directional gate that when activated, fires a slow(ish) projectile that can be shot for an effect.

Besides the obvious answer of "if you're good enough, any map," any location that forces the Raiders into a funnel, or a tight space where they can only either approach you, or run from you. A pretty good example is Short-Fused, where there's only 2 paths that lead to the second tank. This allows you to set up your Einstein-Rosen Bridge and completely stop any forward momentum by the enemy, forcing people to go around the other path to try and flank you. In an example on this map, I held my ground against all four Raiders on the tunnel-side bridge, only losing when their Micah went around to take me out, losing both the keg, 2 of the others lives, and about 25 seconds of time.

• Know where you plan to attack ahead of time. Being a slow moving character, you don't have the ability to change plans on the spot. Although possible, your reaction will be much slower, thus losing you time to delay/defeat the raiders.
  
• Don't waste any time. Even while dead, be watching where they're going, what they're doing, and come up with a plan.
  
• Look to your allies. Are they pushing, or standing their ground? Try and coordinate even just a little with the ai.
  
• Don't play aggressive. Running into their territory is a death sentence unless A. the Raiders are bad, or B. You somehow manage to get the jump on them. Valeria loves to set up her own territory, and keep intruders out.
  
• Try and set up suprise Einstein-Rosen Bridge attacks. If you can place your Bridge in one place, yet be defending down it's line of path, you can surprise the Raiders, generally only once, with a random quantum projectile dropping them.

Little Girl. As great as a consistent aoe of damage is, the single instantaneous burst of damage can knock a local down, and put most others 1-2 hits from down.
Currently, I use Cyclical Effectiveness and Titanium Chassis. Cyclical Effectiveness is high risk high reward, as the longer you are alive, the more damage your shots deal. This can be effective if you're able to stay alive long enough. Titanium Chassis allows you to reposition faster, potentially allowing you to adjust your plans slightly. It also allows you to survive slightly better for Cyclical Effectiveness. My desired replacement card for Titanium Chassis would be Zero Point Energy or Background Radiation. Zero Point Energy grants you health regen while next to your Einstein-Rosen Bridge, or within 15 meters, while Background Radiation causes you to more damage if you are close to the Bridge. Although with either you'd have less repositioning capabilities, you'd have either bonus survivability, or increased killing potential.

I'm going to use the Short-Fused example from earlier, but go into further detail into my thoughts/bullet points.

What I'm thinking about before match has even started:

1. Initial plan of where to attack: Just after the Ravine as they're carrying the canisters. A mob of wardogs spawn, giving the capability to coordinate an attack with multiple allies.
   
2. The Raiders are Micah, Lycus, Hive, and Ayana. Unfortunately for them, Lycus is level 2, while the others are on par with mine. Main threats are Ayana with her grapple, and Hive with her health pool if her ability is full.
   
3. Tanks are positioned in front of cliff-side bridge and behind cave-side bridge. Front tank will be hard to defend.
   
4. Set up the Bridge on the far cliff for suprise explosions from a distance.
   
5. Stealing the keg is an option.
   
6. Suicide with keg is an option (cliff jumping.)
   
7. Killing them isn't the only Victory Condition, stalling until the Wardogs destroy Loaht's hut is another.

What I began to think after the first tank was destroyed:

1. Initial plan of where to attack: Cliff-Side Bridge. It's the easiest path to the tank, therefore the most likely plan of attack.
   
2. (assessments of players) Micah has shown to be good at using her hologram to dodge in CQC. Destroying the Hologram if she deploys is a smart option. Hive doesn't vary her CQC attacks, so predictable. Ayana hasn't used her ability, and enjoys diving deep into enemy territory. Isolated attacks can slowly reduce their Aleph. Lycus doesn't activate his shield. Leave him to the Wardogs, as they kill him easily.
   
3. Best spawn point is on top of the Sniper Post next to the tank.
   
4. Stealing the keg is an option. If I'm able to get it to far-side cliff, it'll be much harder for them to get to it before the timer expires.
   
5. Suicide with keg is an option (cliff jumping.)
   
6. Killing them isn't the only Victory Condition, stalling until the Wardogs destroy Loaht's hut is another.

As the game didn't go on long enough to see the second phase of the match, there's nothing more to say.

• Keep in mind the latency from the host, as it affects your Quantum projectiles.
  
• Valeria is not easy. She's powerful when she gets a shot off, but missing is just as likely, and that's where you'll lose.
  
• Being the Antagonist, especially with Valeria requires a lot of thinking. If you really don't want to work that hard, Valeria is not the choice for you.

It's a game, so have fun!