Hmm, necro but a good one.
Surprised to see only one mention of The Alexandrian. To me, it's by FAR the best, and if I could only pick one, it would be this hands down.
	
	
		
			
				
			
			
				
				Welcome to The Alexandrian!
				
					
						
							
						
					
					thealexandrian.net
				
 
			 
		 
	 
Absolutely amazing stuff. So much of my approach to running a game is from his blog. He started a YouTube channel recently as well.
His tips on running a sandbox, how to handle mysteries, giving clues, etc are priceless. His blog has been around a long time so there is a wealth of info. This is one of my favorites:
	
	
		
			
				
			
			
				
				If you're GMing a roleplaying game, you should never prep a plot.Everyone's tastes are different. These matters are subjective. What works for one person won't necessarily work for another. Yada
				
					
						
							
						
					
					thealexandrian.net