Knowledge is something, once you have achieved it, that cannot be taken away from you. Starting children out as early as possible will help them for the rest of their lives. I sit with my grandchildren (now that I have patience I did not have with my children) and we go through puzzles, books, magazines and toys repeating colors, words and pictures. The same puzzle is put together at the very least three times. All the while repeating colors, pictures and sometimes shapes.
Knowledge is so very inexpensive. Take a walk with the little ones. Repeat colors, name of trees, name of animals, name of any and everything their little eyes are watching.
Pick up any book in your home. Sit and look through the book pointing out pictures, names, letters and numbers.
When riding in a vehicle I usually point out different items and repeat them every time I see it again. I repeat colors on a traffic signal. Red means stop, green means go, yellow means slow down. I repeat traffic signs their color, shape and words.
I repeat words no, hot, stop and I LOVE YOU!, YOU ARE GOOD, mostly I love you, you are my angel. Children gain knowledge just by watching and listening to everything you do. So be careful to give them the right kind of knowledge.
There are so many community resources for books and knowledge for little ones. Your public library is full of tools. Your local schools have programs for you to utilize. Apparently, you can navigate the internet and find many more resources. There are so many different resources that you can use to help you find teaching tools.