counting on your fingers

lots of different methods for counting on your fingers exist, some let you count to 9999 using two hands and others even work out square roots!
The one I like to teach is knuckle counting where you count the knuckles of your four fingers using your thumb. Each finger has a value of three, and this is a number concept children in early childhood can easily add or subtract from. Number concept with 5 find most struggling until they are near  5. Because knuckle counting breaks things into threes rather than fives I feel it works better for this age group.
  Counting is a different skill to manipulating numbers, and most can learn to count to 12 quite easily, fortunately knuckle counting let's you do just that on only one hand.
dividing 12 into 4 lots of three (4 fingers 3 knuckles each ) lays the ground work for multiplication.
Once children can use their thumb to count it also helps develop manual dexterity for things like writing. (Finger games and finger rhymes are important to develop these skills too.)
I like to count left to right (mauī ki matau)  little finger towards index on the right hand, as that's the direction writing goes in. I possibly should count down the fingers for the same reason but filling up the fingers seems more natural and concrete, so I start at the base and move up the finger with my thumb.
When children start to associate each joint with a numeral you can even try adding 1 or 2 or taking one or 2 away to get a new number. eg tip of the ring finger or six, back two equals base of the ring finger or four, but that's pretty advanced stuff.
While the decimal system works well with ten  digits, base twelve was widely used until around 60 years ago 12 pence in a shilling. We still use it for time 12 lots of five = 60 minutes, 12 hours, 12 inches in a foot and counting to 12 still let's you count to ten anyway.