The main thing that you must remember when teaching the child everything must be in the form of a game. Children get tired quickly and start to be distracted and cranky. To avoid this, your lesson should not be longer than 30-40 minutes.
Manual for training needs to be bright and interesting. Such that the child himself dragged them. If the child is less than three years, it can be a soft fabric books with removable liners. This book you can make your own patches, and for the older children. On each card draw a large figure and any items that quantitatively coincide with this figure (two dolls, three apples, etc.). Make a field which will be blank cells and numbers. Put the cards face down. Let the child randomly pulls out a card. Utters aloud a figure that tells what the picture is and puts it into the appropriate field. So he will remember not only quantitative but ordinal numbers.
With older children you can use the cubes and other items in everyday life. Don't forget about the account and in everyday life. Exercise on sweets and fruit. And begin solving with the child small tasks. He had one Apple, you gave him one more, how many apples he has? Or ask the baby if he took five candies and two of them have already been eaten, how many does he have left? Tell me what each digit can be element of the other two (5 plus 2 is three, or 4 plus one). So you teach your kid simple arithmetic tasks.
Play with your child, sometimes deliberately make mistakes and give him the opportunity to correct you. If some task he doesn't do that, don't insist, otherwise you will stop all the hunting for learning. Postpone a difficult task, think themselves as better and clearer to present it? Be sure to praise the kid for his success and encourage. Can even have a normal school diary where you rate it.