Sycra's how to draw teens and children[part1]: [link]
he has other great videos i.e. on folds, male and female proportions etc.
Foervraengd's proportion guide[I used this in the correction]: [link]
some children stock: [link]
books by Andrew Loomis are also a great resource, they're free to download
I said it in the correction, but let me tell you again, guidelines are important. I used to think it was unnecessary, one more thing I have to erase later, but I realized its importance, and it actually makes the drawing process much easier.