If it's tipped too far forward or back, it won't protect you properly. The straps should be snug without pinching. They should be easy to fasten and release. Helmets with four fully adjustable straps are best. Always wear an approved bicycle helmet.
Smart cyclists make themselves easy to see.
If you are out after dark or in fog or rain, make sure motorists can see you. Use the light, reflector and reflective tape required by law and remember a bicycle must be equipped with a bell or horn in good working order. Wear light or bright colours like red, white or yellow. Put an extra bit of reflective tape on the pedals. Wear reflective bands on your wrists and ankles or on the front and back of your jacket.