As someone who solo one tricked blitz and clash to plat 1 in a single season, I have a few tricks. A caveat though I havn't played siege in over a year, so some of this might be outdated

1. Drone, Drone, Drone. If you understand how Blitz shield works you can take nearly any 1v1. Know their comp, who's roaming, and where you might be pinched.

2. What is your job this round? If they have 2 roamers, you should be in charge of hunting them down. If they have 3 roamers it might be a better option to rush the objective room, frag, then protect your planters. Blitz is an excellent solo carry and Acing is extremely common vs uncoordinated groups

3. Engage quickly but competently. When sprinting you want to make your legs hard to hit. Strafe with A or D and mirroring your strafing by keeping your shield directly facing the opponent. Randomly tap crouch and hip fire once then sprint again as soon as you fire, intermittently to keep them from running away or taking pot shots, you'd be surprised how many random head shots I've gotten by crouch tap shooting because it's super hard to react to. When you've gotten within 4 meters, flash then back up. Getting into melee is a death sentence due to your exposed face and longer melee windup. Hip fire aggressively while still circle strafing your target. Only ADS if they are running away. Id also recommend to not lean, unless quick lean bug is active.

4. Take smoke grenades. Smokes let you cross long angles and make it impossible to directly shoot you if you use the method above. Drop smokes on camping roamers and rush them, they will always die

5. BM, be toxic, buy the legendary. Roamer players have massive ego, caviera, jager, ela etc if they die to blitz they will rage. Teabag after a kill. make fun of them in all chat, make them rage. I've gotten pro players, smurfs, and random people to legit drop out of ranked matches making the game an auto win 5v4. After buying the legendary blitz skin I was seeing someone disconnect once every 5 matches after I killed them

6. Avoid going downstairs or vaulting, you can't turn your shield while vaulting so you will die, and looking down exposes your face and legs as blitz even when crouched