[Leon]

I think your question has more to do with "what to get graded" than what to get PSA graded. PSA does a good job overall. If you want to protect a card for some reason, that is a good reason to go with slabbing. If you play the registry game, then that is a reason. If you are reselling and the grading fee is less than the extra value of it being graded, then that is a good reason. If it is a card worth a fair amount then that is a reason. However, many common cards won't have their value raised so they might not be good candidates for grading unless there is some other motivation. Your more common, and not high grade, game cards might not need to have money spent to slab them. It's really just a cost vs value when reselling, to me. Good luck.

I should add, what I described above is my strategy but there are a ton of others. Specifically I don't think those common Polo Ground cards need to be graded unless they are going to be 8s or better.....