- Ideas are not quite entirely worthless, they're just close to it. There are exceptions, however they're very few and very far between. Being able to execute is half the battle, the idea is maybe 1-3%. I was a teenager during the dotcom bubble and I was mesmerized by it. I had to unlearn all sorts of bad notions that the bubble years had imprinted into my brain about how you build Internet companies.

- The concept of knocking down the first bowling pin when building an Internet service, or really any type of business. Also known as finding a market small enough to own when getting started. The smallest segment you need to go down to such that you own a dominant position from which you can move outwards from. Peter Thiel has widely discussed these ideas, and I've always liked Chris Dixon's blog on this:

https://cdixon.org/2010/08/21/the-bowling-pin-strategy

- The various concepts around value investing. It has its own sphere of ideas and approaches to not just equity investing, but understanding how to value something in most any transaction or business in general. From Ben Graham, to Buffett, to Seth Klarman and several others. In my early to mid 20s they hugely influenced how I approach investing and making various financial value judgments.

- Ruthlessly simplify your products. Get down to the most simple form of what your thing is. Remove, remove, remove, remove shit from it until you're afraid you're about to break it, and then remove some more unnecessary shit. Do I really need that feature? No, toss it. Do not add more than necessary until users / customers tell you they absolutely require it, and even then maintain some healthy skepticism that that is actually true. When I was young I used to believe there was immense value in adding to, making something big (and usually complex); the exact opposite is more often true, the value in your concept is unlocked for your audience thanks to simplicity, with complexity acting as a barrier (a form of intense friction) to adoption and understanding.

- Focus is one of the most important things in life. Multi-tasking is bullshit, almost entirely a lie as a concept. When I was in my early 20s I was the type that would persistently get distracted wanting to build all sorts of things. I'd juggle three or four projects at a time, with frequently predictable results. I'd have an idea that intrigued me and off I'd go to build it, with a smattering of other projects in various stages of non-completion. Some of this is chalked up to liking the first 1/2 to 3/4 of a project and disliking what comes after. Maturity was accepting the often unenjoyable grind that is required to make something successful. Losing or splitting focus is disastrous if you want to make something successful. Figure out how to control your focus, hone that skill; it doesn't always have to be set to ON, you can turn it off when you don't need to be so diligent (because it can require a lot of exhaustive effort for some people). I've always liked the generic saying about a diamond: incredible pressure on a small point for a very long time. That's how you make something successful.

- Exceptionally few opinions have any value. Very likely most of the people you know, they're not experts at what you're working on, they probably do not know better than you, their advice is likely worthless; do not take their advice, do not seek their advice as it pertains to the specifics of your area of work. Seeking their advice on broader life-business things or generic business issues, sure, that might make sense. Only seek advice from people that are experts - or as close to it as you can get - on the thing you're seeking advice on. Everyone has an opinion, so if you ask someone, the odds are they'll give it to you, even if they shouldn't due to their own ignorance. People are typically terrible at self-censoring when it comes to throwing around advice about subjects they know little about.