[swarmee]

Some of my recommendations:
1) Check your cards against other ones in the set to make sure they have not been trimmed. If your card comes up trimmed or short, they will return it.
2) Any paper loss knocks a card down to a 1 or 1.5, even if it looks nicer.
3) PSA tells you which centering requirements they have for fronts/backs per grade, so use that to determine which grades you kind of expect. I know you didn't mention Beckett, but they need perfect centering to grade a card a 9.5 Gem Mint. I think PSA only requires 55/45 for a Gem Mint 10.
4) Make an educated guess about your cards and write down your projections. My latest sub all came back a little lower than I expected, but I didn't get some OC qualifiers I expected, so they kind of balanced out.
5) If you're sending cards in bulk, look up their monthly specials. You normally need 50 cards, but the price per card drops from like $13 down to $7 or so. Wait times can get very long though.

I didn't send in any high value cards yet (don't have that many), but I use USPS priority mail boxes with tracking and insurance.