Keep them in mint condition because wear and tear can lower their value
If you're going to make any swaps to this deck, try to keep them simple and refrain from introducing too many new cards , as that will start to widen the pool of possibilities when drawing a card, and you may find yourself hoping to top-deck a certain card that is less likely to show up.
Celebi V #245 Ultra Rare Fusion Strike has quite a few examples of excellent artwork within the Alternate Art category, but the Celebi V Alternate Art for us takes the cake
Well, according to Canada's Toys R Us website, Canadian Toys R Us stores will be giving out a promo card each month for Pokemon's 20th anniversary: Pikachu on February 27th, Tangela on March 19th, Magikarp on April 23rd, Geodude on May 21st, Clefairy on June 18th, Ponyta on July 16th, Meowth on August 20th, and Slowpoke on September 27th