Different methods work for different people. I definitely agree that vocabulary is important when you are first starting. The more words you know the easier it will be to form sentences that you actually need.
I don't care for romanization because it will not give you the correct idea about the pronunciation. I remember 3 years ago I was trying to look up an actor and the letter ㄱ was romanized as both g and k and because of that I was struggling to find the actor because his name started with ㄱ. I couldn't understand how one letter in Korean can be both G and K so I thought it was a different person. I also didn't know about MDL at the time.
I started learning Hangul quite late. I first just started by picking words up while watching kdramas. Now I think Hangul should be learnt as early as possible.
Once you have the basics down, learn about Korean sentence structure and then slowly learn more vocabulary and grammar. Simple grammar at first like present, past, future and formality levels. And also learn the pronunciation rules as you progress.
Duolingo was still okay some time back when they had the discussions available on each sentence. There was so much valuable information in the comments with actual Koreans explaining things. But now it is totally up to you to figure out what is going on. They added very very basic grammar explanations on the Korean course recently. So duolingo cannot be your sole source of learning but it is good for listening and writing practice.
One other option for practice is having a conversation with an AI. A Korean also recommended the naver app for speaking practice recently. Then there are YouTube channels that help with listening and speaking practice. Consuming as much content in Korean as possible is helpful so you pick up how Koreans speak. Imitation is the best start for speaking practice.
Memrise has a decent Korean course but it is all going paid so it's usefulness will decline greatly unless you can afford to pay. But they teach far more natural and useful sentences than duolingo.
There are community courses also which are now moving to a website and I like the one based on Talk To Me In Korean.
A lot of free sources of learning are sadly becoming paid so Youtube still is the best source and some books that you can find pdf versions of if buying them is not a viable option.
But if you can spend money then getting a Korean tutor is probably best especially if you are a high beginner. I feel like leaping into intermediate level is what I am struggling with the most and a Korean tutor would help a lot with that. But I am going to be at it alone as I lack both time and finances at this time. Next best thing is to get other Korean learners who are at a higher level or similar level to ask doubts to. You can also ask doubts to Korean tutors in comment sections. Many of them reply with explanations which are quite helpful. Especially when it comes to grammar.