I've grown chilis for a few years now.

The first year was the best crop, it was a really really really hot summer so had hundreds of chilis to use every week. Ended up freezing most of them in ice cube pallets to keep them for use throughout the year!

The last two years haven't been as good but I think it's mainly because the weather hasn't been quite as good.

So best thing to do I think is keep them as warm as possible at all times. When it's warm outside, let the plants have some outside goodness, when it gets a bit chilly (mind the pun) bring the plants inside.

When the plants are inside though you need to watch out for a black fly that seems to like living on the plants... They'll fill the room that the plants are in if you aren't careful...