Multi-stop long haul - how to get the best deal?

[iisme]

We (2 adults, 2 children) are planning to go to New Zealand for 2/3 months this winter, stopping off in one or two places en route both ways. Does anyone have any tips about how to get the best price on the flights? When should we book? Should we look into each step individually, or does it usually work out best to get a multi-stop flight on, e.g., skyscanner? We'd be very grateful for any advice.

A multistop flight on the same or a codeshare airline worked best for us

Thanks. Did you book directly with the airline?

I tried but I couldn't get the flights I wanted so we ended up using a travel agent
I wanted Quantas as I didn't want a US airline for our US legs (we went via NY & LA)
It was 5 years ago now so I'm sure online booking has improved

Try Travelbag

Ok, thanks. And is as early as possible better or do cheaper flights become available later?

I think earlier is usually better
It depends how much flexibility you have with your dates

Check prices both together and individually. I had a trip to Aus last year flying into one city, internal flight and then flying out of another. The multi-city planner tried to charge me $600 for the internal flight which should have been max. $150, and I think I ended up getting it for about $80. I ended up booking through an online travel agent for the long hauls and booking domestic flight myself separately.

There's a new iPhone app called hopper (I think??) which says it can help to predict price cycles for journeys and tell you when is the best time to book.

Sky Scanner to check prices
Also check direct with airlines

Avoid any major holiday times eg Christmas, New Year, Easter - fly a couple of weeks earlier or later

If you fly mid week it is often 100's cheaper than flying weekends
Avoid mondays and fridays

The earlier you book the cheaper it is and you can choose your seats too

Multi stop with the same airline - cathay? if you plan to stop off in the far east or singapore airlines.
the earlier you book the cheaper it is ime.
Also avoid Chinese New Year if you are coming back via the far east as prices are insane then! 2017 CNY is January 28th so would avoid the whole of the week after this.