I found a lot of this information very difficult to find. Basically I had no idea what I was doing nor who to ask for help. Here is some information and links I wish I had to set up your business if you are at square one. 

Register your business -
To be honest all this shit goes straight over my head. Deciding whether to start a business, a company or a trust is a personal choice that you need to decide depending on the needs of your business. I paid someone to set up a trust and company for me from which I registered MEW Clothing under as a businesses.
Register for an ABN and/or  a business name here.
Bank -
It is quite easy to set up a bank account and link it to your personal one once you have an ABN. Just talk to your local bank to do this. I use NAB because they have low fees.
Accounting -
I recommend using Xero to do your bookkeeping to do as much as you can do yourself. There is lot of information online on how to use the program, and for $26 a month you can organise your finances and lodge your quarterly BAS. This stuff is confusing, so I recommend speaking with an accountant or bookkeeper first, or doing a lot of research.
Trademark -
Through IP Australia you can apply for a trademark. This is a confusing process but if you spend the time reading their guides you will get there. My trademark cost me $330 for one year.
Website -
Use Shopify. I originally went through a web developer who set up my store via Wordpress and Elementor but the website always had problems and the software made it was difficult to update myself. When I sought IT help, I was advised to chuck the whole thing and start fresh on Shopify, and I can attest it is much easier to design and run myself. It is also relatively cheap - $29 USD a month for the basic plan which is good enough to be used by big businesses. When setting up you can use a free theme or pay $180 USD for a better one. I bought one because I wanted some of the pro features like the option to incorporate my social media. To be honest, I didn't need it. Whether you choose to use a free one or buy one, I have been advised to use the same one from the start, as it is can be problematic changing themes later on. 
I set up and run the website myself.
HOT TIP - I was also advised that websites like WIX or Squarespace are the worst and should be avoided at all costs.
Domain -
You can buy your domain on websites such as GoDaddy or you may be able to do it via Shopify. If you are using Shopify to set up your website, I suggest following their advice so you don't have to switch your domain over later. In terms of email, Shopify cannot host domain email, so you will need a third part such as Gsuit. Confusing, I know, but you can get there. Talk to Shopify help - they are great.
Marketing -
At the start I was using Instagram and Facebook ads as my main mode of marketing. I don't think I made a single sale through them. I think sharing posts and following people online to gain a following is the best thing. Expect to grow slowly. It is advisable to create a ‘unicorn’ customer - your target customer if you could sum them up as one person. You then aim your ads at this type of person. I found this hard to define, so I use Instagram analytics to tell me who my customers are. I was also told to make sure I grow an organic following of at least 1,000 followers before paying for ads, else Facebook will know you rely on them for followers and make it hard/expensive for you. I did this by finding pages like small business owners Geelong or @bossbabesgeelong and following all their followers. These people get it and so are likely to follow back. Beware - follow too many people in one hit and Facebook will think you are a spambot, so space it out - 200 a day is your limit, but over time this will add up. There is so much to know in this field so I suggest paying someone for a chat to understand some basics, as without proper marketing your business will never reach people.
I would also suggest creating cool content, I personally think this is the most important thing.
Photography -
All of my campaign photos are taken on my Canon X9 and iPhone. I edit them on  a free app called Snapseed. All of my professional photos are taken by my Aunty Margaret Metcalfe in her studio, and I am grateful she has offered to do this for free. If you are lacking money perhaps you could find students who need subjects for school photos and make your shoots fun to give them creative content as well.
Postage -
This was bloody confusing. Eventually I went with Sendle. It was simpler and seems to be cheaper and quicker. You can link them with your Shopify account so when you get an order, the label is available on Shopify to print on the website. Makes it easy. I also use Hero Packaging for postal packs as they are biodegradable, although Sendle sells some as well.
Business cards/stickers/stationary -
To start I used Vistaprint because they are so easy and cheap, but eventually I would like to find local businesses to do.
Stickers -
Someone recommended Rad Stickers to me because I saw their business sticker was still in perfect condition on a street pole after two years of being there. 

Starting a Fashion Line
I have no experience in fashion. None. I didn't even do textiles in high school, let alone at uni. My mum taught me to sew and I did an online course outlining the basics. I’m a big believer that you don’t need to be taught art. But I did have to teach myself everything myself about how to start my own line. This is what I learnt.
1 - First thing is first - design and sew the item. If you don't sew it, you won't know if the design or material works.
2 - Draw the item digitally. I literally use a Microsoft Paint equivalent on my mac.
3 - Create a tech pack. This is a document containing all the information on how to construct the item. This includes the fabric type and colour, images detailing construction and all the measurements needed to construct. You send this to the manufacturer. Most manufacturers provide size grading themselves so you don’t need all the details some tech packs say you do, like the weight of the fabric. Manufactures definitely need tech packs, so my suggestion is to use a template and learn how to make them yourself, become some places charge at least $120USD per tech pack to make them for you. I use this template, which I edit in Paint. I edit each page separately, then on my mac I open all the images at once to compile them then click 'Print' → 'Save to pdf' to create a pdf file.
4 - Find a manufacturer. Google is your friend here, as well as Alibaba.
5 - Negotiate. You can negotiate MOQ (minimum order quantity) and price. Once an agreement is made, you will be quoted the price per unit (which changes depending on how many units you order) and price for a sample.
6 - Sample. The sample can be made and sent to you - this can take 1-2 months. Once you get your sample, you can give feedback to improve and keep having samples made until you are happy. You then proceed with the bulk order once you are happy. The Samples cost around $120 USD each (again, negotiable).
From here you wait for your items to arrive. Don’t forget to think about where you will store them (I ordered 350 items which came in 9 boxes). After that you will need to photograph, upload to the website, market, and then send them off. 

There is a lot to learn and teach yourself, but once you understand you are able to move. At the very least, having this knowledge puts you far ahead of others. I think what you need the most is the drive, the passion, and the vision. If this feels right to you, as does the timing, then don't let the hard work put you off. I've just cut a lot out for you. What will really making you the one who will get to where you want to go is having the balls to do it. And even if it doesn't work out, this knowledge is handy to have for life, or a future project. I read once that on average it takes five failed businesses to launch a successful one. Keep going. You'll know when the moment is right. MEW Clothing is my second business, and I have that feeling with MEW. So fingers crossed I will beat the statistic. 

One final tip is to please, for the love of God, if you are unsure, try Googling the answer before hassling your friends and family.

Much love, 
-mew