about 70% are feminine. There are asome suffixes that always make nouns of one gender (-тель makes masculine nouns for "professions" and "doers"; -ость makes abstract feminine nouns).
Unfortunately, suffixes will only help you at later stages when you encounter many words constructed this way from simpler words. Amongst the top-2000 list most -ь-ending words cannot be analyzed this way.
Ah, there is also an orthographical trick. If a noun ends in a hush consonant (Ш, Ж, Щ, Ч), it will only have a soft sign if it is feminine:
- FEM: ночь, дочь, мышь
- MASC: нож, луч
Nope, lined paper is also OK. We use it in our Russian and Russian literature classes. However, the usage of тетрадь still suggests you are talking about a notebook with the page size similar to that of a book, and the one opening horizontally.
A notebook with pages flipping up and down, often small, is «блокнот». There are things we would call a «блокнот» that open just like a notebook used in schools—in this case, such notebooks are smaller in size, typically fitting in your pocket.
I believe it's more than co-incidental that the idea of "four-ness" is also present in the Spanish and French words for exercise book. The Russian тетрадь is derived from Ancient Greek τετράδιον (tetrádion) while cuaderno and cahier come from Post-classical Latin quaternus. The Greek and Latin words both relate to "a set of four" -- I think it has to do with the way that large sheets of paper were folded and cut to make smaller ones. The English paper size "quire" also comes from the same source as cahier.