I started with Duolingo. I actually bought a year subscription, it was cheap for me. And since it's a family sharing subscription, two people can use it same subscription on their device. I did lessons there for 2 hours everyday for half-year. That helped me to learn to read/prononce words, pick up vocabulary and listen to phrases being said while reading them from the screen.
What I regret is that I didn't type words but taped on words to fill out the blanks. I don't know if this is available on the phone app. 100% it was available in the browser. It made it harder to spell correctly later on. Many words resemble English ones, but spelling is a bit different. For example, "gouvernement" - "government", "collègue" - "colleague", etc.
Verbs are the heart of French language, so conjugating them correctly cannot be emphasised enough. When you learnt verbs, learn them with prepositions they go with like "àider à = to help", not just "aider = to help", "discuter de = to discuss", not just "discuter = to discuss". There's no logic or silver bullet but memorising here.
Same with nouns - their gender is just something you need to hear, say and write enough times for each word to stick in your mind as masculine or feminine. There are some tricks with endings, but it's not much of help to be honest.
Another great sources, once you already now a bit of words, is Chatterbug - app, free. They have short video records on grammar topics.
Basically, to make use of language automatic, you need to repeat things enough times. Again, once you have learnt the basics, I recommend channel Fralaland on youtube. Repeat many times after the videos and it'll stick.
I'm not sure about 100% free options. I ended up paying a tutor since I wanted results faster.
