Re: counting only aces and 5's and 6's
There's a book called "Blackjack Bluebook" by Fred Renzy. It discusses various counting systems from balanced to unbalanced but it also includes a count called "The Ace/10 Front Count", where you'd only count aces and tens. It's geared more towards the 6 deck game and only provides a very tiny and I repeat tiny edge. Your chances of being wiped out are good.
For historical purposes, let me state that Ken Uston in his book "Million Dollar Blackjack" has a count called "The Ace-Five Count" where all you'd count are aces and fives. This count is geared more towards the single deck game, your edge is tiny and I don't think it's for the single deck game offered today as it was written back in the 1980's.
Since you also asked for a count easier than Hi-Lo, Bootlegger is right, the Knock-out count and Red Seven are both easier, but there's something else that's even simpler but it's not really counting. There's a book called "Golden Touch Blackjack Revolution" by Frank Scoblete. It presents a system called "Speed Count" where all you have to do is add up all the small cards and them subtract the total from the number of hands being played. The number you arrive at tells you whether or not to increase your bet. The book comes with a CD that you can practice with. This is not traditional card counting but it's easy to learn.
If you're interested in Speed Count but don't want to buy the book, Arnold Snyder's blackjack website, www.blackjackforumonline.com teaches a count called "OPPC". It's similar to Speed Count and they teach it for free on the website. On the home page you can click on it to start learning. OPPC is not card counting. Like I said, it's similar to Scoblete's Speed Count.
If all you wan't to do is count aces and another card I'd suggest you go with Fred Renzy's Ace-10 front count in the book "Blackjack Bluebook 2". Remember your edge is tiny, you'll more than likely be wiped out, but hey, it's better than nothing. Even if you decide not to learn the ace-ten frontcount Blackjack Bluebook 2 is still a good book to get because it exposes all of the myths that regular players at the tables beleive in, it has a section on camoflauge and how you should act at the tables that really is excellent compared to other books that have sections on camo, and it teaches simple unbalanced counts like Kiss 1, Kiss 2, and Kiss 3 to a balanced level 2 count called "Mentor".
Hope this helps. Tell the Queen I said Hi, and tell Fergie we don't care about her weight issues.