I'm going to bypass any helmet debate here and just assume that if you're putting a helmet on your child then you're doing so wanting it to be effective, rather than to satisfy the letter of the local law. If so, please, please, please snug up those straps! There are SO many kids out there with dangling helmet straps. That leaves the helmet next-to-useless in a crash, where it will slip off the part of the body you're hoping to protect, and possibly harmful, if the helmet were to catch on something and get pulled behind your child's head.
Before adjusting the straps, make sure the helmet fits. Ideally you should be able to adjust the snugness so it doesn't fall off with straps unbuckled.
Next, get the angle correct. The front of the helmet should be low on the forehead, not jauntily at the hairline or down in their eyes. Your child should see the brim of the helmet when he/she looks up with their eyes.The straps should be even, and each make a "V" with the bottoms just below their ears.
Finally, and this is the hard part, snug up the straps so that only 1-2 fingers can fit, and so that your child can feel the straps tighten when opening their mouth fully.That last part is hard for kids with sensory issues, who are resistant to helmets in general, who are used to loose straps, or who have been pinched in the past. Oh, the guilt I have about the times I've pinched Drew buckling her helmet. She won't let me forget it.
Be very cautious when buckling, have them look up and close their mouth, and use your own finger as a "pinchguard". Then gradually snug up the straps a bit more with each ride.
Need a quick 1-2-3 helmet fit test? Just remember the eyes, ears, and mouth part.
When it's cold out, the models with ear flaps are great, but you can also use a hoodie top or thin wool cap to keep little heads and ears warm. Bulky hats and hoods interfere with helmet fit, though.In the category of "safety advice based on ultra-rare occurences", the safety people would like me to warn you that bike helmets are not for general play, especially on playground equipment, where a handful of children have snagged their helmet dropping through narrow spaces.
Starting young, letting your child help pick the helmet, modeling helmet wearing yourself, and being consistent about their usage may reduce helmet battles. In your house, that is, not online.
