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.
Evaluation Tips
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.
Limited Tips
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.
Team Building
Build a team with people you trust. You need to trust each others opinions and track record.
 
Improvement
Consume as much content as you can. There's so much free content out there.
Magic Resource
Channel Fireball - Josh's weekly video
Interview Links
Star City Games
Connect With Josh McClain
@Good_Game_
jmcclain2007@hotmail.com
Like What You Hear?
If you like the show, head on over to iTunes and leave an honest Rating & Review.
Let me know what you like and what I can do better so I can make the show the best it can be and continue bringing you valuable content.
I read every single one and look forward to your feedback.