A project home company will do all of this for you and the fees are included in the final price of the house. If you plan to go to a project home company with a Designers/Architects plan tell them or you may end up paying for things twice. A boutique builder is much more flexible and will often work with the Designer/Architect to complete some of the steps.
The steps are similar whether going to a Designer or an Architect, the only difference may be you may need to find a drafts-person to draw the Architects plans. Most Designers are drafts-people or unregistered architects, and if they aren't I would question their training.
Step 1 - Initial meeting with the designer
Be clear what you want out of your designer, do you want a design or a drafts-person to draw up your design. Your designer will want to know how you live, what rooms you want, hobbies, pets, cooking habits, entertaining habits or wants, what you hate and love about your existing house. It is helpful if you have written this all down before hand so the designer can review it while designing. Be clear on the importance of items, often not every desire can be incorporated and it helps to know what to leave out. This first meeting is important because it allows the designer get a handle on your personality about what you want out of a house. I prefer to meet in the clients house, this is especially important with a renovation.
A site measure will be required for a renovation.
Step 2 - Survey
Always order a survey early in the process, it helps the designer an enormous amount and will be required for shire. In the last few years shires have become very strict about surveys and even the smallest renovation needs one. They take at least 3 weeks to get done and will cost about $700 give or take a few hundred. Most CAD programs will read a DWG file so ask your surveyor for one, they will understand what you are talking about.
Step 3 - Design
The Designer will complete the design and have a number of meetings, phone calls or email back and forths to get the design right. Depending on the job and the client this stage can take a few weeks to several months.
Step 4 - Final Plans
When you are happy with the design the Designer will clean up the plan and prepare it for the next steps.
Step 5 - Costing
This is where you take the plans to builders to get them costed, I suggest no more than 3 builders. It can be quite hard to compare costings because builders include different things. You can ask for special things to be itemized, your designer should help you with this.
The following will happen but whether you see them will depend on the builder. Some builders have their own drafts-people that take over from here, some will get the designer to create working drawings. Give the builder your designers details so they can contact them directly.
Step 5a - Developer approval
In some new sub divisions the developer needs to approve the plans, you would have been given this information when buying the site.
Step 5 - Planning
A separate planning approval only needs to be obtained if you think there is going to be an issue with codes, it does speed the process up with new houses if you do this while the costings are happening. The designer or builder can help you with this. There is a fee you can see on your local shire website along with the form required, allow 6 weeks to 6 months for jobs that don't comply to zoning conditions.
Step 6 - Engineering Plans
The Shire require an engineers stamp on all plans, it may be a simple footing detail or full structural plans depending on the scale of the job, any where from $450 to $2000 and about 3 weeks. The builder usually takes care of this, the only time I have done it was for owner builders. The Engineer will need special plans from the designer/drafts-person.
Step 7 - Energy rating
The dreaded energy ratings no one wants to deal with, hopefully your builder will have a person to do this for you. If the shire will allow it, Deemed To Satisfy is an easier method but you wont know your star rating. The are many accredited companies in Perth offering this service.
Step 8 - Building licence
Once you have your Builder, Planning approval, Engineers plans and energy rating you can apply for a Building licence. The form is available on your local shire website and are fairly straight forward once you find it. There is a fee involved and you will need to sign it even if your builder prepares all the paper work. This can take 6-8 weeks.
Step 9 - Water authority
The builder/plumber has always taken care of this on jobs I have worked but all plans need to be approved by the water authority.
Now you are ready to go to site, this process can take up to a year, more if you have troubles with shire. If you are demolishing and building new you only have to move out 6 weeks before it goes to site so give it time and don't move out too early. Most of these steps require money to change hands, your builder will cover some of them, included in their deposit but it is a good idea to have the budget to deal with them. I also recommend at least a basic landscape plan before you build, this will prevent costly retrofits such as power points for retic down the track.