Here in NLIn The Netherlands kids have an orange flag attached to their bike making the young, vulnerable (and inexperienced) biker more noticeable and signaling that the biker is young and inexperienced:
(Sorry, photo ofthere's a kid as I couldn't find another, no offence meant w.r.t. your biking abilities)vulnerable road user present:
(Sorry, I couldn't find another photo of the flag so I used this photo of a kid. No offence meant w.r.t. your biking abilities)
The flag "pole" is flexible and by its wobbly movement attracts more attention to the flag. Perhaps you can attach such a flag with the letter A on it to signal you're a new biker?
As noted in the comments, recumbent bicycles also use these in NL, so it's not only for young/inexperienced riders.
Apparently Erlkoenig already noted this idea in a comment, but I didn't seeonly saw that comment only afterafter I posted this answer.