I highly recommend R. Aryeh Carmell’s sefer, known unofficially in yeshivos as “the small white book”, it’s called “siyata legamara”, it has a list of very common terms and how they’re used; it’s easy to memorize and is presented in a very clear format.
I’ve learned with adults who have started in their 40s…they are mechaven to rishonim and can learn tosfos just like anyone else! Never give up!