Short answer: the usual answer is to start with a classic, simple game like Pong. If you see a lot of beginners making Pong games, that's due to an old article by a well-known game developer advising exactly that.

Of course, you don't have to literally make Pong. Shoot'em ups are very easy to make, if hard to make fun; other people recommend platformers, or falling block games. Visual novels, too, if you can manage the art requirements. Or heck, text adventures.

Either way, make the games you want to play. That's key. If you're not very fond of playing games, then why bother making any. I had surprising success with roguelikes and text-based RPGs, and in certain circles even with text-based strategies, before I moved on to making tools.

Speaking of which: try other tools, too. See what works for you and your team-mates, and can produce games you like without too much effort. Don't put your eggs in a single basket.

Just don't set your expectations too high, because making money from games is hard, never mind making a living. Good luck, but have a plan.

It is difficult to answer because what may work well for one person may not work well for another.

But my personal recommendations.

First, find a community of developers in your language. This way you can communicate more easily with people who have experience.

Second, don't create a team with friends just because. Normally friends are usually enthusiastic and supportive at the beginning, but creating games is a job that ends up consuming a lot of time. Most people end up losing interest (I'm not saying that it will happen to you, since all people are different, I'm just telling you what commonly happens.)
From what I understand, creating games is your idea, not your friends'.

If you don't have any experience, try joining a JAM and collaborating on a team (you can try participating with your friends), that way you can quickly learn a little about the basics and how complex it can be to create a game. JAM are usually focused on a topic and with a time limit, which will help focus on something specific.

Personally I would never pay for a tutorial, these days it's full of great free stuff if you take the time to look and that money can be used on something more useful like licensing music, code or art which can be much more useful .

Personally I would not use unity3D, that is, if you consider that it is the best option for you, go ahead, but I have the impression that you have not done the home work. I recommend you look at the pros and cons of the most popular engines and choose the one that best suits your needs.

Not even 30 yet? You are young, and really it's not too late until you've passed on from this life. Don't compare yourself to people who struck gold when they were younger than you. It is totally pointless, you can't go back to when you were 18 and try again. You can only act TODAY. It doesn't matter if you are 30, 40, or 70... you can still be a game developer.

I saw a great video by the Math Sorcerer on youtube, about this exact topic. He was of course referring to learning math but the concept applies to pretty much anything. He related a story in which he was teaching a night class, so all of the students were a little older and had jobs and families to take care of during the day, but had decided to go back to school and were taking this math class. Anyway he started asking them how long it had been since they took a math class. One guy was over 50 years old and said it had been 30 years since he last took a math class. 30 years!

Another story in that same video involved a fellow professor who was much older, who remarked that when he was in college he could study for 8 hours straight, but now that he was old he could only do about 4 hours of intense math focus. So yeah, you might slow down a bit, but think about that... this guy in his elder years (I think 70s) was able to read advanced math papers for a solid 4 hours.

One thing that "keeps people young" is to continue doing such work, continue learning, continue growing. As you go through life you will realize that the people who can barely get off the couch at 60 years old are usually that way because they have been sitting on the couch for the last few decades. When you resign yourself to a stagnant life, your mind and body follow suit. If you tell yourself "I can't learn anything new" and stop trying, the process of learning becomes more and more difficult. Just like when you stop using a muscle, it weakens over time.

On the other hand there are people out there who are 60, 70, 80 years old and still learning, still doing the things they love, still moving. I play in a band with a drummer who just turned 75. He still carries his drums (we do help him, lol), he still learns new songs, and he's always ready to keep playing. So many times at practice the rest of us have said "ok, it's getting late, we should pack up" and he's like "I could keep going!". 

So anyway that's my rant about age, it isn't nearly as important as people make it out to be. What is important is that you keep using your faculties and pursuing new things. I won't say exactly how old I am (not very) but I can already see some of my peers basically giving up on life, ready to just "stay in their lane." But for me, I've been developing games as a hobby since I was very young, and only now (couple decades later...) am I really starting to put my work out into the world and trying to maybe make a career out of it. Some days it feels exhausting, and I do have a lot more responsibility than I did when I was 16. But it is also exciting to be still learning new things and keeping the dream alive. It makes me feel alive when other people my age seem dead inside, and that's worthwhile on its own regardless of how many sales or how popular any of my projects get.