From personal experience I think English speakers have troubles approaching synthetic languages in general because the English language is very analytic. I lurk

From personal experience I think English speakers have troubles approaching synthetic languages in general because the English language is very analytic. I lurk in a few language-learning forums and I try to help anglophones learning French from time to time, they're often overwhelmed by the conjugations and to a lesser extent the grammatical genders which are omnipresent in French grammar. On the other hand I've been studying Russian pretty intensely over the past year or so, so I can definitely empathize with the frustration of having to learn a complex case system. I think the important thing is: it doesn't really matter if you get it completely right (or even mostly wrong). As long as you build simple sentences a native speaker will be able to figure out what you're trying to say. If somebody asks me "tu parlons anglais ?" it's definitely going to sound very wrong to me but I'll probably be able to figure out what you're attempting to communicate. I think it's worth it to actually learn the declension/conjugation tables to familiarize yourself with them but you have to face the fact that you'll probably never learn to use them correctly just by memorizing rules. Eventually as you encounter them IRL you'll start to develop a feel for it. I wonder if the average English speaker would be able to explain why they say "if I were you" and not "if I am you". Yet few get it wrong. More generally I find that the main difficulty in learning languages is, by far, vocabulary. You can often get by with a surprisingly low amount of grammar if you understand what the words mean.