A dream of mine is to design and build my own house. Aside from listing unusual features i want, like Tatooine-style sunken rooms for insulation or a connected greenhouse, i don't know where to start.

How should i decide dimensions? How should i draw plans? Are there checklists to make sure i don't forget something important like a bathroom? How complete can a design be before i have a specific place in mind to build it?

I have designed my own house twice. The first was unconventional, as it was rammed earth. The second, much more conventional as I had to cater to a wife and family.

Start by sketching it out. Forget dimensions, a rough sketch. You will get it wrong and want to move things, add others, re-think sizes, so sketch it again.

Do this as many times as needed until it feels right, then think about drawing it to scale, with dimensions included.

Be aware that unconventional buildings immediately disqualifies a lot of contractors, even curved walls can be challenging for some.

Things to remember: wet areas being close together cuts costs, you need a point for services to come in, you will need to meet your local building code. Eventually you’ll need professionally drawn plans, so make sure you are prepared to work with an architect which may mean compromising some of your vision.

Property needs to be secured before plans are finalised, because there will be different gradients, soil types, drainage requirements, street setbacks etc to deal with

Local library, get a book about building a house, build house.

Get someone else to pour the foundation though, you really want that done correctly.

(Disclaimer: I'm not an architect; I just used to watch way too much HGTV.)

How complete can a design be before i have a specific place in mind to build it?

It could be completely complete if necessary, but I would advise the opposite: start with the site and design the house to suit it. Think about things like access, sightlines/views, neighbors, slope, orientation relative to the sun, etc. and go from there.

Take a map of the site and scribble a bubble diagram on it in order to figure out the relationships between the spaces, then refine that into an actual floorplan.

Also, do some research on architectural styles, even if you want to build something weird, because you need to understand the rules before you can break them in ways that make sense. I recommend https://www.goodreads.com/book/show/10812979-get-your-house-right .