Sequence of chess openings

Piece placement, and pawn structure.

Good Chess Openings Books for Beginners and Beyond...

https://www.chess.com/blog/RussBell/good-chess-openings-books-for-beginners-and-beyond

In particular, check out Discovering Chess Openings by John Emms....

Challenge me in daily chess, I'll teach you opening..

https://web.archive.org/web/20140708112658/http://www.chesscafe.com/text/review315.pdf

About half a century ago, I think the Fine book was considered to be nearly essential reading, but now, I fear that its information is seriously out-of-date. Also, I do not think it has much in the way of sample games.

https://www.chess.com/forum/view/chess-openings/how-do-you-learn-openings-2?page=3

Anyway, I do not get the impression that it was the intention of arjunchhabra to ask about how to go about learning an opening.

I do not think that there is any generally approved sequence of openings for learning. For those trying to give you advice, it might be helpful if you said something about what you have been doing so far. Also, why are you thinking about going on to something else in a sequence? Here is one person's commentary, indicating how one's chess opening choice might evolve:

http://www.uschess.org/content/view/11634/675

Thank you so much for your replies. It's certainly illuminating. 

Some opening repertoire suggestions by GM Nigel Davies and IM Andrew Martin...
http://www.chesspublishing.com/content/repert.htm

http://www.chesspublishing.com/content/repert2.htm

Choosing an opening repertoire....

http://www.mark-weeks.com/aboutcom/aa02i07.htm

http://grandpatzerchess.blogspot.com/2007/03/openings-for-improving-players-part-1.html

http://grandpatzerchess.blogspot.com/2007/03/openings-for-improving-players-part-2.html

http://grandpatzerchess.blogspot.com/2007/03/openings-for-improving-players-part-3.html