There is a multitude of things that can be suggested, changed, done better etc etc.
I will try with a competly different proposal - based on my own very recent experiences:
I play on a Huge galaxy map with everything abundant and research on normal.
What about trying a medium map and maybe research on slow/very slow and/or common/accassional habitable planets?
Why I suggest this is following: So far I *always* played medium (and once small I think). Just now I'm playing my very first game on "huge"...and that's quite tough as I find I need to be planning much more ahead (like when warships take 5+ weeks to get from the production planets to the front (or where the front once has been)
I usually also prefer research at slow/very slow as this achieves 2 things:
The frequency with which you got to design/change/update/scrap your ships gets noticeably lower. Furthermore combined with the 1-point-Creativity ability pick it's probably the most powerful ability you can pick (imagine getting that 50-turn research project finished after 3 or 4 turns with some luck). esp. when you say
"I'm really just lost in the vastness of the tech tree" I'd say: pick the slowest research setting so you can slowly get used to the techs.
Last but not least, it's completly personal taste, but a Huge galaxy AND abundant settings for stars/planets/habitable planets would probably be my personal hell
I can easil see somebody getting overwhelmed by the number of stars/planets such a galaxy holds.
That's why either put the amount of planets (esp. habitable planets) much lower in a Huge galaxy or play on a smaller galaxy (medium?) with abundant/common settings.
There's enough to learn even without having to manage 500 planets