If assistance is required, the cow or heifer should be restrained in a clean, well-lit area with good footing. The area should be located so that the cow can be easily moved and adequately restrained. Be clean and gentle. Determine the position of the calf by identifying the feet, head, or tail. If those are not present do not pull.
Common problems are a leg back or head back.
Pulling the calf before it is properly positioned will make the problem much worse. Timely professional assistance could mean the difference between a live and dead calf. After delivery of the calf, clear the throat and mouth of mucus. A piece of straw can be used to tickle the nostril. Let the cow lick and clean the calf so that they will bond.