Sometimes children learning two languages learn fewer words in each language at first. But they will catch up by the time they are 4 or 5 years old. Make learning fun. Do not punish or force children to learn another language. Use books, games, songs, poems and riddles.
Children learn language best from someone who speaks it well.
Speak to your children in your native language. Use the language you know the most. This way the children can keep the two languages separate. Do not speak baby talk in any language . Take time to explain a word that your children do not understand.