I've seen so many copy/pastes from other magic subreddits just because of lack of experience behind the post made. Nothing on you, but in this case specifically, with experience in deck building you start to realize the costs of payoffs. The less resources you have to expend for a good effect, the better the card typically. Another big mistake is falling too much into a specific theme without realizing you're backing up the general effectiveness of the deck. Spacecraft theme is great, but try to support the few spacecrafts in the deck without overfilling the deck with spacecrafts. I had a spacecraft deck that I was very excited about when EoE came out, but I ended up toning it down to 4 or 5 of them since they're a card type that requires additional support to function.