Punishing your child for every little rule that is bent, will only lead to a power struggle and possible tantrums. Sending your child to her room should only happen when she has broken a big household rule. This should only happen about once a day. Should it occur more often, then your child might be bored, so some time outside to work off some pent-up energy could help.
As far as safety is concerned, as your child becomes more physically capable, you should become strict about certain safety rules. For instance, insist on your child wearing a helmet to ride her tricycle - this will help when she is older and needs to wear one while riding her bicycle.
Knives and other sharp objects should be kept well out of reach of your child, and remember, at this stage they are very adept at climbing! The car seat must be used every time your child travels in the car. If she has learned to open the safety catch herself, then make it very clear that the car will not move unless she is properly harnessed in.
Medicines should be locked away - your child can climb, so simply putting them high up will not work. Also, playgrounds are great, but make sure that the surfaces under the playground equipment are safe.