You should be all set as long as you have your riding gear. full face BMX helmet for ece 22.05 motorcycle helmet, and wrist guards are the bare minimum IMO. From there you can get knee guards, elbow guards, and a motorcycle jacket/bmx jacket if you wanted. I also recommend getting a hand mirror like this: https://www.amazon.com/gp/product/B000TCGD96 makes me feel so much safer riding on the street. I also recommend either getting a armband phone mount or a smartwatch to monitor your speed while riding, I feel a lot a safer, especially at low battery, when I can look at my arm and see how fast I'm going in EUC World
A motorcycle helmet and one of these mirrors does the trick for me. (mirror goes over your wrist guard)
I just use on of these on my non dominant hand, over my wrist guards. For me that's my left wrist and here in the U.S. I'm normally riding on the right hand side of the road as a cyclist would so, lifting up my left wrist gives me a clear look at traffic coming behind.
https://www.amazon.com/CIPA-11125-Hand-Mirror/dp/B000TCGD96
This is the mirror I’ve been using on my wrist. Works well for me so far.
However, there was a time when I was trying to raise my left wrist to check the mirror, there was bicyclist trying to quickly pass me on my left side and I almost back fisted him in the face.
https://smile.amazon.com/CIPA-11125-Hand-Mirror/dp/B000TCGD96
Just add 1 hole in the back of the shell to mount it nicely on the wrist guard
this. big fan of this wrist mirror mounted vertically on my wrist guard with the widest part further away from my body to allow me to see around my helmet more easily.
https://smile.amazon.com/CIPA-11125-Hand-Mirror/dp/B000TCGD96
I had to make 1 small hole in the back to adapt it to the wrist guard comfortably
I got mine from Amazon, CIPA 11125 Hand Mirror https://www.amazon.com/dp/B000TCGD96/ref=cm_sw_r_cp_api_i_9lsrFbZ1QZCSZ
I look back a lot. If there's a lot of traffic I try to get on the sidewalk if there is one.
You can also get a wrist mirror like this or this, assuming you ride regular it can be a help (goofy riders are at a natural advantage in US traffic I feel). I sometimes use one of these if I am dealing with a lot of heavy traffic or visual "noise", since it helps keep your eyes forward - you use it like you would a car mirror, which is for an initial check to see if there's anything even approaching. If it looks clear, THEN you do a quick over the shoulder glance before you move from your "lane".
You should definitely learn to look back. Also, Try one of these. https://www.amazon.com/dp/B000TCGD96?_encoding=UTF8&psc=1&ref_=cm_sw_r_ud_dp_E3KZM0H6P8C1SCC63MPM
This is the mirror myself and a lot of local riders use, doesn't attach the same way as OP's but I like it
https://www.amazon.com/gp/product/B000TCGD96/
CIPA 11125 Hand Mirror https://www.amazon.com/dp/B000TCGD96/ref=cm_sw_r_cp_api_glt_fabc_PP69EDECEN5EBQZ8TT9Z