Make sure you have studied all of the relevant parts of books and videos on this topic, many of which contain clear diagrams of the expected event. Don't get worried, in most cases, goats manage perfectly well on their own and any help that is needed is minimal.
It is worthwhile to collect together a set of items which might be needed during the actual kidding, or immediately afterwards. Many of them could be put in one box, to be ready at a moments notice.
The recommended list includes:
A bucket for warm water
A bar of soap and nailbrush
Some veterinary obstetric lubricant gel
Some clean cotton towels
Roll of paper kitchen towels
A pair of sharp surgical scissors
An antibiotic spray obtained from your vet
A stomach tube and syringe for colostrum feeding
Kid feeding bottle, teat and a half litre plastic jug
The goat's pen should be well cleaned and disinfected at least a week before kidding.
A low hurdle should be available to section off a corner in the kidding pen, should it be thought to be advisable to protect the kids from being trampled on etc. The dam should be able to see, smell and lick her kids, even if they are placed behind the temporary partition.
On hand should be the telephone numbers of at least one vet, and at least one experienced goatkeeper or shepherd and a mobile phone if no permanent phone is nearby.
As soon as the first signs of birth are observed, remove the water receptacle from the kidding pen until after parturition is complete.