Basically you want to try to get into 1v1s, make sure you pounce to heal or to secure a kill and reset your pounce. If you're still low pounce away and use prowl to heal yourself slightly until you get into safety. Being airborne above the enemies heads makes it easier to attack them and harder to attack you, especially towards enemies who have a limited range such as Moji.
Alternately you could act as a skirmisher when within team fights, being a general pest to the enemies chipping away at their health as they are distracted by your team, and then getting out of combat once you accumulate to much damage or your team ends up losing. Basically keeping yourself alive long enough and not letting your enemies secure a kill against you is key, especially if you have a high kill streak. Of course this isn't fool proof and you can easily get cornered with your abilities down, almost always guaranteeing your death. It might be a good idea if you solely want to play as a skirmisher you stick to a tank when the round starts, giving your enemies a bigger target since you have less value on the team than your tank does.
Note: This build does get weaker the longer the game drags on due to anti-heal, you are strongest at the start of the game so take advantage of that.
Savagery
Pounce
Heal for 140 after using Pounce.
Level 2
Predation
Armor
Reduce the Cooldown of Prowl by 0.4s each time you hit an enemy with a dagger.
Level 2
Shred
Pounce
Reduce the Cooldown of Pounce by 2.5s.
Level 5
Persistence
Armor
Reduce the damage you take by 12% while at or below 40% Health.
Level 3
Walk it Off
Prowl
Heal for 120 every 1s while Prowl is active.
Level 3
Rogue's Gambit
Armor
Increase the damage done by Pounce by 15%, reduce its Cooldown by 2s, and reset Pounce's Cooldown after earning an Elimination.
Level 1
Nimble
Armor
Gain 21% Movement Speed.
Level 3
Chronos
Armor
Reduce the Cooldown of all your abilities by 20%.
Level 2
It is paramount that you get as much mobility as possible, this will make fleeing combat easier. Also chronos will be a useful tool, the less ability cooldown time the more you can heal and pounce.
Life Rip
Weapon
Your weapon shots gain +20% Lifesteal.
Level 2
Life Rip
Weapon
Your weapon shots gain +30% Lifesteal.
Level 3
Kill to Heal
Armor
Getting a kill or elimination heals you for 400 Health, unaffected by Anti-Healing.
Level 2
Kill to Heal
Armor
Getting a kill or elimination heals you for 600 Health, unaffected by Anti-Healing.
Level 3
You do 400 damage per dagger, getting life rip will give you a decent chunk of healing, that healing can be a deciding factor of a 1v1 or can be used to take pot shots against enemies while fleeing to heal a bit if your prowl is down.
The true healing you get can be very useful mid to late game, especially since you don't need to get the elimination yourself. Also anti-heal late game can be debilitating to this build.
You should always have at least 1 of these 2 items at least at tier 2 if you can help it.
Haven
Armor
Reduce the Damage you take from Direct and Area of Effect attacks by 6%.
Level 1
Veteran
Armor
Increase your base maximum Health by 5.5%.
Level 1
Wrecker
Weapon
Your weapon attacks deal 30% increased Damage to Shields.
Level 1
Resilience
Armor
Reduce the duration and effectiveness of Crowd Control and Slows by 25%.
Level 1
Haven is not really useful for this build, i usually suggest against it unless you are often taking damage no matter where you go.
Veteran is kind of useless, getting a % bonus to your already small hp pool is something that won't help too often, and will seldom increase your longevity.
Wrecker should really only be used if the enemy team is doing a lot of shielding which is actively hindering your team's dps to do damage to tanks, then again your tanks, dps, and supports should be taking this instead of you so you can focus on flanking.
Only take resilience if getting stunned is actively making it so you can't do anything at all.
Atlas and Azaan should not want to prioritize you, especially if you are airborne, because then they would have to waste their time attacking you instead of focusing on bigger threats like opposing tanks, of course this does not really work in solo 1v1s or if you are rushing point (which as a flank you should never do unless it secures overtime for the rest of your team.)
Yag, Term, and Makoa are just weak to you due to their size and your mobility. Yagoroth would have to stop whatever she was planning to do just to chase you, which in that case you have won since you have distracted her from supporting her team with her massive aoe attacks to attack you, a lowly flank. Terminus is a melee character, with his ranged attacks not being as good as his melee, if you can make him use his shield against you then he is easily open against attacks from your team, and if not then he has no choice but to take damage from you, not only that but you can get out of his ult with a single pounce. Finally Makoa's shield is easily ignored, you can close the distance and get inside it, sure if he hooks you its game over unless you are 1v1ing him but he should pose no issues otherwise.
Opposing Maeve's (that don't use this loadout) you should have the edge on since you effectively have more health, given you both are equal on skill level of course.
Skye can't do much since she is ground bound, Skye excels when her target is nearby on the ground, not hovering around her like a bug.
Nessa and Strix are just weak against being flanked in general, their long range damage excels over their close range damage making them awful in mid to close range combat than other operators.
Struggles against Torv and Willow because the can shut down her healing. Moreso against Torvald who can put an anchor down on her by restricting her mobility. Willow can also shut down a potential 1v1 with her anti-heal aoe while healing herself turning the tides in her favor
Using your mobility as defense is worthless against characters who can automatically hit you, Moreso Rei since she specializes in turning 1v1s into her favor
Io, Furia, Corvus, and Seris aren't as huge threats but still can be good counters to any Maeve, due to their ability to stun you and easily kill you since Maeve in general is frail.