Parents with 2 or more toddler kids, how do you discourage jealousy among your children?

Since they're both too young, whenever we are together, I let them feel how both of them are loved. I also try to explain to our first born that he should love his sister because she is his best friend. I guess it's more of building the relationship and love between the siblings first, so they won't feel any insecurity even if you spend time with the other.