First I go to google and try to find a good picture with a white background.
I try to find the biggest one I can, and try to find one that’s “iconic” (which usually just means it shows up a lot) if there is an obvious iconic one.
Then I put it into Inkscape and use the “Trace Path” function.
Mess with the threshold number until you find one that looks like the picture (You’ll need to trace each time, sorry).
Sometimes you’ll need to use multiple traces to make it work.
After you slap it all together, make it blue and use the ellipse function to make a white circle behind it. (pg dn to move it down a layer) then select everything and hit ctrl+G to group it and make it 400 pixels tall, and then it’s ready for the poster!