Josh McClain has 4 Grand Prix top 8s including winning Grand Prix Detroit in 2013 (Modern format). He also has one Pro Tour top 16 and a TCG Invitational win.
Check to see if new cards fill holes in existing decks.
Check if powerful cards that weren't played before now have synergy and are playable with the new cards.
Sealed: Sealed is bomb-centric, so removal is very important. Stand alone cards that are good on their are will perform better than synergy decks.
Draft: Draft cards that work well on their own and if the synergy comes it's a bonus. Draft a lot to hone your evaluation eye. Group discussion is also crucial to improving.
Build a team with people you trust. You need to trust each others opinions and track record.
Consume as much content as you can. There's so much free content out there.
Channel Fireball - Josh's weekly video
Star City Games
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