Hello P0rtalFTW and welcome to TASvideos
Unfortunately, the goal choice of this run is kind of pointless, as in the second quest, nothing changes that significantly changes the TAS. You can effectively copy and paste the entire input from the first half to the second half without any problems, making you effectively just run through the same game twice.
The run also had a few technical mistakes which made it not up to par, in particular:
1.You noticably bump into walls and perform walljumps in several places where it is unneeded, which slows you down needlessly.
2.The 4-2 warp zone glitch can be done considerably faster.
3.Various minor slowdowns, such as in the Water in 8-4.
You also point out you want to learn the flagpole glitch, which is basically essential for publications to perform.
You should check out the published runs by
HappyLee to see how 4-2 is done optimally. There's also a
Game Resources page for Super Mario Bros, showing all the major tricks in this game. You might also want to post WIPs and stuff in the SMB forum thread before submitting them, as that will allow you to get more detailed feedback.
For a first run, this wasn't so bad, but it wasn't quite there yet. Keep trying!