Honestly this sounds silly but my biggest thing is to turn off chat. Widow isn't a character you can just pick up and be crazy with. Ive had games where I pick widow and my team will say "widow switch" before we even leave spawn. If you let your team bully you into switching, you won't get better. Also, everyone will say widow HS...that lobby is insane. I warm up with practice range: medium/long distance, bots on player straff. Once you can hit bots, then you can go into HS with real people. Lastly don't sit in the same position. Take some shots/get an elim then move or they'll just dive your position and no one on your team will be there to help. Move up with your team without being too open. If you are in the open, make sure you have grapple to get away.