I suggest ELGOI system in Metropolis. Many veldspar, not common Troig squads, and a refiniry to compress in it.
Avoid systems near trade hubs, especially Jita. They are always mined dry.
Go for example into Minmatar space around Rens and you will find many untouched belts.
Ah! Missed that, apologies. Was going on the OP, sounded like he was focused on hisec.
Yes, further away from major trading hubs and with higher quality ore, that changes the risk/beneft payoff. But that’s a bit ambitious for a new player in solo, yeah? They’d need to join a corp for that.