Classical music is an amazing kaleidoscope of eras and styles and golden-chain influences (that last idea belongs to George Grove, not me!) and all you can do is to listen and enjoy whatever bits of it you like best. A little scholarship goes a long way but, as with any music, you can enjoy it on many levels. I wouldn't worry about trying to remember what's what. That comes sooner or later if you've been listening a lot. Buy yourself a box set of Beethoven symphonies (I recommend the cycle conducted by Riccardo Chailly) and play 'em to death in your car or while you're eating your cornflakes. Grab a few discs of Mozart symphonies too (the "best" ones are numbers 36, 38, 39, 40 and 41) and a few of his piano concertos (my favourites are all of them from no 17 onward, that's eleven in all, but for sheer joy just nos. 21 and 23 will set you on fire). Delve into some non-orchestral music too - try both sets of Schubert Impromptus for solo piano, D899 and D935, very approachable and lyrical. Then there's Bach's Mass in B minor, unsurpassable, his Brandenburg Concertos, violin concertos, Cello suites, any Bach really. My two very favourite concertos are Beethoven's Emperor Concerto and Dvorak's Cello Concerto. I think I'm coming across as a lyricism-lover...!