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For deck size, I would say to start with 105. After you've played a few games, try to think if there were any cards you never used at all because A) you always had a better option or B) they would not have helped even as a last resort option. If you identify such cards, take them out. Then consider if there were any cards that you really wished you would have had in multiple different situations and games. If you can identify any, add them in, otherwise keep the deck as trim as possible.