If farrowing inside during winter: have heat lamp in creep area, with nice amount of straw. Radio is nice addition too.
If farrowing inside during summer: still have radio, heat lamp to be on day and night for the first 5 days and then reduce for just night time. Heat lamp maybe too much for summer. Perhaps a little night lamp on every night for three weeks just so everybody can see each other.
Farrowing outdoors in winter: ensure you have plastic curtains, arks are facing against the prevailing winds and you may also find that a fender (little fence for the outside of the ark) will be useful to place outside. A suitable farrowing ark size would be 8ft wide by 6ft long. Also to raise the lip of the entrance to the pig ark to prevent any piglets losing their way in the dark and accidentally falling out of the ark.
Farrowing outdoors in summer: same as above you may wish to keep the plastic curtains down to prevent predators until the piglets are say three weeks old.