It makes little to no difference that you don't have a degree. The web and design content covered in university is a joke, and most students are only capable of working with skeleton code anyway.
Udemy is the place to start. Grab a bunch of courses on sale and have fun with them. The better courses make the learning experience a million times more enjoyable and comprehensible than university. Be sure to grab a course on making quality website mockups. And grab some based purely on the included projects. If you want to be full stack you need ambitious projects. I strongly recommend the Python language and Django framework. Python can be used for just about anything, is more 'English-like' than most languages and Django can be used single-handedly to build a complex site. Instagram was originally built on Django and last I checked is still primarily based on it. Hosting complex Django sites is a breeze thanks to affordable web app hosting services.
On a related note, pay no mind to the people here hating on devs who use templates. It is insanity to take an approach that only original development should be used for all engagements. Most clients cannot afford the financial cost and time delay of that. At the very least, much of your own work will form templates that you reuse anyway. I don't necessarily recommend WordPress, as even the better implementations always seem to have something off about them, but Joomla 4 is amazing and will let you provide your clients will a very professional back-end for adding content.
As far as your income aspirations go, I recommend finding a niche. Simply building run of the mill websites is generally for suckers.
These are likely to make you more money:
- eCommerce websites
- custom integrations
- specialising in ERP/integrated solutions
From my experience, your best bet is fully managed integrated eCommerce solutions. Finding clients is relatively easy - successful businesses that are well suited for eCommerce but are crap or non-existent in that area. You can mockup what their website could look like to get your proposal stuck in their head and there's a good chance that they want everything handled for them. So website dev, ongoing support, hosting, cloud-based email, storage and backup, eCommerce functions incl returns & ticket support, integration with POS and any ERP, courier integration, social media advertising (which is a technical skill to do correctly, with targeted ads, A/B testing and refined market data over time) and super duper search engine optimisation (not overly difficult to destroy the competition with proper SEO backlink networks - most devs ignore the importance of domain authority - to rank in top 10 for desired queries). These ultra comprehensive packages are loved by successful businesses, because they don't have to admit how terrible their tech situation currently is.
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Edit: I forgot to mention that the above paragraph is how more than a few Chief Information Officers had their start. Initially you will spend quite a while, if not an indefinite period, focusing on a single client due to the workload and being a relative noob. If you do an outstanding job and become indispensable, there's a good chance that the company will produce a juicy offer for you to join them full time to handle the entire eCommerce side of the business. You would not believe how many companies are sick up to their eyeballs of hiring tech people who can only talk the talk. If you're a star they won't give a damn about your qualifications. So you'll also have this additional potential route of becoming a top level employee.
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If there's one skill that I have never seen someone develop though, it's an eye for good design. Being full stack will require a good eye. Both for your proposals but also in everything you develop and comment on. I really hope your ideas for stuff genuinely look good, that you pay attention to detail and that you can identify how bad 99% of stuff on the web is. Make sure you understand colour. Go through the Shopify blog for a treasure trove of useful articles.
Best of luck!