toughest thing
The toughest thing for me when counting is dealing with distractions and forgetting the count as a result. Have your friend engage you in a conversation with the music blaring so you can barely hear him. Then after a minute or so, see if you still have the count right. While playing, you'll have to deal with distractions in the form of players talking to you, getting drinks from waitresses, dealing with security adding more chips to the dealers chip rack, people going apes on you because you hit your 12 vs. the dealer 4 while at 3rd base and as a result the dealer didn't break, buddies calling you on the cell, the wife/ g/f leaning over and kissing you while asking you how you're doing and sometimes casino heat.