It's a good idea but my hope is that everyone will be
extremely cautious on
FB &
IG. As soon as I started my
IG account I had another user who sold counterfeits follow me. I wanted to quit & I was only ONE day old!

I used to tune in to several
FB groups & the soiled rags I saw being auctioned off (& the newbie bidding wars) sickened me. It's great that
SM has almost been like a healthy shot-in-the arm for the coin/paper money hobby but it's also has a dark side (ie: it's the WILD WILD WEST). Loads of misinformation & bad advice (over graded & hyped up auction items) disturbs us old conservative guys who like to do things the old tried/true way.
In general, I would caution any serious collector against using
SM as "a guiding light" to collecting (or acquiring). Some of the youtube videos I've seen (on washing polymer banknotes, coins, etc) are really disturbing. Plus all sorts of misleading hype on fantasy & zero Euros! (or finding "broken ladders," soiled star & web notes, etc). Some collector's criteria aren't negotiable. Many coins/banknotes just aren't that collectible. Stick to Forums (like here on Numista, CCF or others) where you will get conservative advice from real (maybe old fashioned) but honest collectors who want to see you develop goals, acquire slowly & cautiously a fine collection. You've got lots of time, so a bit of education goes a LONG, long way.
Re: eBay
There is this
BEST eBAY &
BAD eBay sellers thread on NUMISTA
There is this
E_commerce thread on
CCF
On
my site, I created a
Money Market page which give tips (& what to avoid) as well as 7 eBay BIN sellers who have served me well over the past 4 years. (>scroll down to my Dec 29th entry<). Each eBay seller mentioned has a link to that seller (if you want to check out what they have but some sellers have since suspended their sales due to the pandemic). Mostly banknotes.
Hope that helps!