If all you want is quick improvement then there will be some stop gap methods. Eventually the answer is "improve your normal chess to improve your blitz." Ok with that disclaimer out of the way:
Learn a solid system and play it every game. This will allow you to play quickly in the opening and spend most of your time in the middlegame. Even better if it lets you do a paint-by-numbers type of attack. I'm thinking like a stonewall or london.
In general lower rated players capture too much. If your opponent isn't forcing you to capture then just ignore their move and look for one of your inactive pieces (especially a piece on the back rank) and improve its position.
Tactics always help. Solve some puzzles every day if you can. Always review the puzzles you missed. Even better if you review them again a few days later.
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This next tip may be useful but it's less general.
I see you thought for almost 2 minutes before moving Qb3, so this tip's main purpose is to help you save time.
Whenever it seems your opponent is going to win something and you can't stop it, and maybe you feel a bit desperate, the type of move you're looking for is a threat (or check).
It helps to start with the big ones. Can you play a check? Well, no (QxB+ makes no sense).
Ok, next biggest is a queen threat. Can you threaten black's queen? Yes you can, with Nc3.
Now a line like Nc3 Qc5 Nb3 Bxa4 Nxc5 Bxc5 Nxa4 might be too hard for you to calculate, but since it's desperation time you're forced to try something and hope it works out. What I'm getting at is not finding Nc3 after almost 2 minutes means you probably were calculating random things instead of looking for the biggest threats you could make.
Now the move you did play, Qb3, takes advantage of the fact that after black captures your knight b7 is undefended. That's a nice concept even if it didn't work out in that position, so that's pretty good, but if you remember to look for big threats to wiggle your way out of a mess I think it could help you save time.
I have been stuck around 1000 blitz rating for a while with highest rating approximately 1075. I have started recently trying to use same openings for more rapid improvement (English Opening & Two Knights Defense). What would you recommend to quickly go from ~1000 to ~1200 blitz rating? Thank you!