Some of it is rather learning the basics of plants.
Stems
Rosettes
Rhizomed
Mosses/floating
Umm.. what do cryptocorenes fall under?
And then some major classifications
Stems - hygrophilas, rotalas, ludwigias, etc.
Rosettes - Echinodorus, Saggitaria, etc.
Rhizomed - java ferns, bolbitis, anubias, etc.
Crypts... well.. are crypts....
Then realize.
Most stems grow forever. They never stop going vertical, need to be trimmed. Light needs here can vary inredibly widely, as can fert needs.
Rosettes are sword plants, and grasses, in various heights. Tenellus micro gets 2" tall. Val nana gets 3' tall. You don't trim them, they grow. Smaller they are, the more light they typically need. Swords are also rosettes, and are huge in variability.
Rhizomes are typically low light plants, with the exception of maybe some Lagenandras. They grow by the rhizome growing. Cut the rhizome to propogate.
Crypts are crypts. I know they have a little rhizome stick, but I think of them as their own class. Almost all are low light.
Here is how I learned it.
I looked up easy to grow plants. I used plantgeek, and aquaticplantcentral, and plantedtank.net
I got decent at making them grow.
I looked up intermediate plants. Same sites. I tried some.
I looked up difficult plants. I killed most of them.
But by the time I'd gone through them, in under a year, I know most of them now. I know in general names for me to stay away from for me specifically - and I know what I grow passingly well. I know what plants I can try in higher light setups - like, I WILL be growing out Aromatica when I get the right setup for it, as well as downoi - and I know now what people mean by high light, fert needy, etc.... because I tried some, researched some, and yes, killed some.
End of the day - what I'm saying is do a little leg work. It really does help. Then, odds are, if you don't have a clue what the plant is or have never seen it - you'll probably kill it, but also probably learn from killing it. Baby steps.