i think reading is a good way to accumulate knowledge

قال تعالى: ﴿ اقْرأْ بِاسْمِ رَبِّكَ الَّذِي خَلَقَ ﴿1 ﴾ خَلَقَ الإِنسَانَ مِنْ عَلَقٍ ﴿2 ﴾ اقْرَأْ وَرَبُّكَ الأَكْرَمُ ﴿3 ﴾ الَّذِي عَلَّمَ بِالْقَلَمِ ﴿4 ﴾ عَلَّمَ الإِنسَانَ مَا لَمْ يَعْلَمْ ﴿5 ﴾ ﴾ [العلق: 1- 5] All you need is reading Belal, and you'll have the knowledge you want. Of course you can't have many information about every thing, but pick the subjects you like to know about and put a schedule for yourself and read about them as much as you can, after a while you'll find it easier to open a discussion about them. But if by any chance, someone open a subject with you that you don't know much about, then it's really ok to say: "I don't know" and you might just want to be a good a listener :) there's no shame in that :)