Keep a technical blog
About 20% of the time, when I Duck for the answer to a technical problem online, I find it on somebody's blog. The other 80% is obviously found on StackOverflow. But software development would be much harder without those people who keep technical blogs/notebooks online!
Here are some reasons you should start a tech blog:
Save yourself a headache - I consult my own blog regularly enough to know that it's effective. When I solve a tricky problem and document the answer here, I'm likely to come back to it. If I hadn't written it down, I'd just be banging my head on the desk going "what was that thing??? That I did?? To fix... the .... aaaaaaa-" - and you get the picture with that one.
Increased value to your employer - Not only will you save your future self, you will save your (present and future) colleagues. Plus, documentation provides a value to your employer which is normally tough to wring out of developers. By keeping a blog you are supporting the team and helping them to grow skills, and (potentially) come on board with new technologies more quickly.
Increased employability - A tech blog showcases skill, knowledge, and the aforementioned value you bring to a team. It also demonstrates interest in your field and a willingness to grow as a developer inside and outside of work. As an interviewer, I would be inclined towards any candidate with an active blog, GitHub, or StackOverflow profile, because I can see you are engaging with your profession.
Developers support developers - How often have you wanted to take a functioning solution back in time to when your project was struggling? You can be this help for someone else, and if we all did more, we would all have more support, and we'd save more time. Help the community out and post your learnings and advice online!
Value to the economy - If someone finds your post online and it saves them half a day, you just created an extra half-day of developer effort which otherwise would not have existed. This is good for the economy. If we all have more time, we all make solutions faster, and the tech sector grows more quickly. This is good for you individually, and your employer, and your local tech network, and the online developer community at large.
In conclusion, start a tech blog. It doesn't matter what platform. It doesn't matter if it's not polished and perfect. Start a tech blog!