We picked the plan and land in June, signed everything in December, building started in January and was finished in July.

We've never gone over budget, but we were very careful and researched everything we wanted included beforehand.

As above we didn't have any, we went through a building company who gave us a price which included everything we asked for.

The only things I would do differently come down to design and size, the first house we built was "ok" but I would have made the kitchen a bit bigger, etc.

I think the key is research, I went and looked at the bath I wanted, the tiles, etc and went to the builder with that info because our first builder usually gave you a choice based on what level of finish you picked. Also to go check the site out regularly if you can, DH and I went around after the block work was done and stood out the front for 30mins trying to work out what was wrong because it didn't look right, they had put the windows in at half height! Also to write a list of everything you've liked about past houses, I found this was helpful when picking a plan or designing the house because we knew we wanted bedrooms in a particular spot and x amount of cupboard space in the kitchen and so on.

Hope that helps, if I think of anything else I'll add it later