1) Learn some accounting first. I see a ton of truly weird debates about economics and taxes that are based completely false ideas of basic accounting concepts.

2) If you use DEGIRO as a broker, make sure you understand the tax implications of their cash handling. They keep customer "cash" in a money market fund, not in a bank account. This is especially relevant if you hold foreign currency in your account. It's also relevant if the amount of disposals in each tax year has consequences for your tax return (such as the £45000 threshold for submitting a CGT return in the UK).

(NB it's a half-finished side project right now)

I'm no longer a contractor, although I have been, and I'm frequently asked by my new employers to provide estimates for dev tasks.

Trouble is, businesses/clients tend to see an estimate as a promise, or a target. From the developer's point of view it is hard to do anything other than guessing (at smaller and smaller granularities). Book recommendation: "The Clean Coder" by Robert C. Martin - esp. Chapter 10)

I started building https://www.estigator.com to see if I could learn React, and come up with something to help me illustrate just exactly who's taking a risk when we say something like "it'll probably take about 3.5 days"

I wasn't quite ready to "Show HN" with this one, but your question made me think of it straight away. Would love to know what people think

[0] https://ffffound.com

[1] https://en.wikipedia.org/wiki/FFFFOUND!

[2] https://news.ycombinator.com/item?id=14204960

So... Burning Shark.