First of all, in a reality where theme decks centered on a set of well-defined card groups are superior to good stuff decks made of general-purpose cards, you should try to steal the opponent's cards unless you are lucky and the opponent is holding a power card that can be included in any deck, such as Haru Urara
Is there any part of the Pokmon TCG standard rotation youd change
Getting them graded can definitely help prove your cards are legitimate, but youll still need to back up their worth with quotes from other buyers, PSAs price guide and other sources when negotiating to get the best deal
During the End Phase, if this card is in the GY because it was destroyed, while in your possession, by an opponent's card and sent there this turn: You can Special Summon this card, but banish it when it leaves the field
If there are relevant creatures that need to be dealt with, it makes sense to swap your Shriekhorns for Lightning Axes
Those evaluations even go as deep as the type of deck youre building, too