If I count my years studying japanese on my high school, I think I've been studying about... 6 years, and I still have hard time to read manga.
At the moment I attend weekly class near my college, since the class only have two students (including me) the pace is pretty quick. I couldn't count how much kanji I've been memorizing, but I assume it would be around 300-400. I'm now pretty familiar with common kanji, I could say I'm still 2nd grader of elementary school though!
Anyway, it seems the quickest way to memorize kanji is to figure out the meaning behind the symbols, I usually device my own mnemonic.
Also, you could (mis)use your japanese by
navigating japanese sites to find some obscure stuff we couldn't usually find in english speaking forums. Fandoms, mp3, doujinshis, whatever, they will help you to recall the kanjis you have encountered. Don't worry if you don't understand bit of what they wrote though, the most importance is, it could help us memorize common kanji. Also, try to find a japanese friend, force yourself to speak in japanese. You could also force yourself to read raw version of manga scans you have previously read.
Last but not least, try to have your own dictionary. I recommend you to purchase
Kanji Dictionary by Mark Spahn and Wolfgang Hadamitzky, the dictionary is pretty thick and could grow you muscle with its gigantic 1750 pages, but you could virtually find all kanji, since it listed 47,000 character compounds.
I bought mine not too long ago only for... $5. I wish I had known the original price is that expensive. I could fetch some quick cash on eBay
And of course, the key of all is patience. We don't need to feel inferior to these who could is fluent already because they have probably live in japan and getting fluent because they speak japanese everyday since we take formal class after all, with much limited time compared to them.
Jam it back in, in the dark.