The hardest part is starting, because it's hard to know where to begin (Grammar? Pronunciation? Characters?)
I would say just pick one and run with it, and you'll naturally move into the other areas as you need.
So for example if you start by learning pinyin (the romanisation of the pronunciation), you'll learn about how they represent tones, and then there may be a section about how the characters give 'clues' on how to pronounce them (the common example is 妈(吗)麻马骂 mā, má, ma3, mà) and before you know it you've learnt about radicals + components. Honestly it's a good place to start.
The first few months are going to be oversimplified in any case so it's largely a matter of getting the ball rolling, and you may have to 'unlearn' some things down the track* these may be deliberately glossed over so you don't get discouraged.
Self study (free):
Chinese grammar wiki to learn the structure
italki for language partners online
WeChat to add them if they're actually cool and follow articles/content creators
meetup or other event platforms to find IRL language practice events
Anki to learn the first 250/500/1000 most basic characters by sight †
You should aim to learn with traditional materials until you get to HSK3 , then you'll have more of a foundation for self-directed learning.
If you can afford it, getting a 1:1 online tutor, and trying out a few tutors until you find someone you gel with can be the difference between foundering around hopelessly and actually achieving something in your first year of study. I can't share the platforms I used (one no longer exists, the other is too niche/local). Some may be students of Teaching Chinese as an Acquired Language and want to build up experience, so they'll have good formal teaching techniques, others may just be looking for some money on the side and could offer things like 'conversation class' which could be more or less your speed depending on your budget/learning preferences.
If you want to practise hand writing, you can use manual spaced repetition:
use a 田 block notebook to practise writing out the characters using a 'guess and check' method (write the correct character on one side with the pinykn then cover up either the character or the pinyin. Go down the list trying to write each character or meaning from memory and then when you get to the end of the column, compare and revise. Write in missing characters/strokes/components/definition with a red pen, circle the mistakes and then continue. If you get a character right three times in a row, you can put it aside and add a new one in its place. After one week, revise all the ones you successfully got three times. After one month do the same for all that month. I used this method before my HSK exam
I did some free online tutoring for beginner students, and I'll have a look for them and if I find them and can anonymise it, I'll try to share here if you're interested.
`* (e.g. the b sound in pinyin isn't actually the same as an English b, it's an unaspirated p, the tongue placement for some consonants is different too, but honestly it's no biggie, e.g. there are more than four tones because there's neutral tone and sandhi where tones merge, e.g. not all characters are 型声 component sound characters)
† I say characters not words, because the aim here isn't to learn 250/500/1000 words but the characters that make up words. Your vocabulary will be much larger because many Chinese words are made up of characters e.g. 手 shou hand + 机 ji machine = shouji cellphone/mobile phone. 飞 fei fly + 机 ji machine = aeroplane. If your approach were to treat shouji and feiji as discrete words, you'd miss out on recognising ji as the key for learning 'machine'. Your deck should have words and their break down into characters and focus on combinations of the most commonly used 250/500/1000 to facilitate those 'ah ha' moments. It's not quite exponential but as you learn more characters there's gunna be more instances where you can guess the meaning of new words just by looking at what their components are.
Don't try to use anki to learn phrases, it's disingenuous because you learn to parrot sentences in their entirety without really digesting them i.e. imo it's better to learn 你 ni you + 去 qu go + 哪里 nali where rather than 你去哪里 'where are you going'?
I'm sorry it couldn't be more like a study guide, it's more just an assembly of thoughts I threw together on the bus ride this morning. I think my main takeaway for self learning is just start somewhere, because if you spend too long trying to find the perfect one-stop-shop starting point 1) you'll never find it and 2) you're wasting useful time. If you spend that time following a thread for a month or so, even if you need to slightly course correct down the line, you'll be miles ahead of the people who tried to optimise their first step.