Once you get going, document all the things you do and hear that are useful to your learning; the observations you have, how using a particular tool benefits your work (does it make a process faster? Improve analysis?). Even if the tool you’re learning doesn’t quite help you meet certain goals, note that down too—it’s a lesson the whole team can learn from.
As you say, the martech space moves quickly. Trends rise and level out, upstart tools get acquired, and if you’re exploring a new capability area, there’s no guarantee the tool you learn will be one the industry settles on.
For that reason, don’t stress about where the market’s heading; focus on the tech that interests you and helps to achieve your goals. You’ll pick up transferable skills that apply across technologies; like learning a language, it gets easier after the first one. Just keep going.
You’ve got this,