1000-1300 rated openings for black

Against e4 you can learn a particular variation of the Sicilian like the dragon variation or the najdorf variation. These are very standard openings against e4 and gives black good counterplay. Against d4 you may try simple openings like Queens gambit declined or you may even choose some complex openings like the kings Indian defence or the benko gambit.

The KID/Modern/Pirc/Robatsch defense is an universal opening vs virtually everything. 

Around 2010, IM John Watson wrote, "... For players with very limited experience, ... the Sicilian Defence ... normally leaves you with little room to manoeuvre and is best left until your positional skills develop. ... I'm still not excited about my students playing the Sicilian Defence at [the stage where they have a moderate level of experience and some opening competence], because it almost always means playing with less space and development, and in some cases with exotic and not particularly instructive pawn-structures. ... if you're taking the Sicilian up at [say, 1700 Elo and above], you should put in a lot of serious study time, as well as commit to playing it for a few years. ..."
In 2014, Pete Tamburro wrote, "... You will see [in Openings for Amateurs] the reply to 1.e4 to be the great reply of the open games with 1...e5. The Sicilian Dragon is presented as an alternative. ... I have found that scholastic players take to the Sicilian Dragon very quickly. ... A cautionary note: the Dragon is good at club level, but as you start facing better players you're going to find yourself memorizing tons of lines and the latest analysis, ... From my experience with coaching players below 1800, you won't need to do that too much. ..."
"As a professional player, I participate in many opens. I need at least 7.5/9 for the first place so I have little margin for mistakes. ... It suffices to mention the 6.Bg5-attack with forced variations all the way up to move thirty or more, to understand my reluctance to use the Najdorf. ... The Dragon is even more unfit for a main repertoire. The same long narrow forced variations, many dead drawn endgames in some lines without h4, and on top of all - the unbearable sight of the d5-square, where one White piece replaces another. ..." - GM Alexander Delchev (2006)

"Generally speaking, 'Starting Out' and 'Sicilian Najdorf' are not exactly words that one envisions in the same title, because anyone who is just starting out should not dive into the vast ocean of theory that is the Najdorf. For beginners, the time invested in studying even minor lines can be more productively used solving tactical puzzles and basic endgame technique.
...
... In some lines, a good understanding of basic principles will take you far, while in others, such as the Poisoned Pawn (6 Bg5 e6 7 f4 Qb6!?), memorization is a must, as one wrong move can cost you the game in the blink of an eye. ..." - FM Carsten Hansen (2006)
https://web.archive.org/web/20140626175558/http://www.chesscafe.com/text/hansen87.pdf

Possibly helpful:
First Steps 1 e4 e5
https://www.everymanchess.com/downloadable/download/sample/sample_id/149/
Starting Out: Open Games by GM Glenn Flear (2010)
https://web.archive.org/web/20140626232452/http://www.chesscafe.com/text/hansen134.pdf
Starting Out: Ruy Lopez by John Shaw (2003)
https://web.archive.org/web/20140627024240/http://www.chesscafe.com/text/hansen53.pdf
Playing 1.e4 e5 - A Classical Repertoire by Nikolaos Ntirlis (2016)
http://www.qualitychess.co.uk/ebooks/Playing1e4e5-excerpt.pdf

yes, I really think you should. relatively  easy openings to learn would be the French against e4 and Queen's Gambit Declined against d4. of course "learning an opening" doesn't mean that you should learn complex lines that are 20 moves deep, but you should definitely learn the basic ideas of these openings and the standard moves (this will probably take less than 2 hours per opening) middle games are much more essential at your level, but a good opening ist still important.

that's kinda true, but KID and Pirc for example have completely different ideas and concepts. If you play a Pirc like a KID (pawn storm on the kingside) you will be smashed off the board by any half-decent player

The KID and Modern are recommended for players 1800 OTB or higher. They are very complex and they are almost useless to a beginner who will not be able to correctly time and execute the necessary tactical breakthroughs.  They are especially bad for beginners because they neglect the center and rely on direct, well-timed counter attacks, and those rely on excellent tactical precision, otherwise the beginner is in a cramped -1 position with no idea how to proceed.

https://www.chess.com/forum/view/general/hey-noobs-forget-openings-study-tactics-the-right-way

First Steps: The French
https://www.newinchess.com/media/wysiwyg/product_pdf/7611.pdf
https://new.uschess.org/news/how-to-really-learn-an-opening-review-first-steps-the-french/

KID and Pirc are introduced as suggestions for Black in Winning Chess Openings by GM Yasser Seirawan.

https://web.archive.org/web/20140627132508/http://www.chesscafe.com/text/hansen173.pdf

You can pick an opening as white and a couple of defenses as black to stick with, and you can look at master level games in that opening on chessgames.com but if you are devoting significant effort to studying openings under 1800 you are just wasting your time... I got to be a top 100 USCF rated player in my state of 8 million people from complete amateur in under 3 years without touching an opening book.  Don't waste your time on openings <1800, it is not teaching you chess, and when chess 960 becomes more popular than chess, all of your time will have been wasted.  TACTICS TACTICS TACTICS!

To a large extent, First Steps books are collections of games, together with explanations.

@kindaspongey Are you getting paid to advertise these books? You seem to promote them a lot, but we all know 80-90% of an amateur's study time should be on strictly tactics puzzles

"... everyone is different, so what works for one person may likely fail with another ..." - NM Dan Heisman

No.

Everyone is also the same, we have the same neural-networks that learn through identification, evaluation and solidification of patterns.  Tactics puzzles are basically taking the most critical moment of a chess game and compacting it into a chess problem.  Show me a chess master who hasn't done thousands of tactics puzzles!

"... This book is the first volume in a series of manuals designed for players who are building the foundations of their chess knowledge. The reader will receive the necessary basic knowledge in six areas of the game - tactcs, positional play, strategy, the calculation of variations, the opening and the endgame. ... To make the book entertaining and varied, I have mixed up these different areas, ..." - GM Artur Yusupov

Don't people differ in how much effort they require and where their best abilities lie?

Is anyone advocating that one not do lots of work on tactics?

"Yes, you can easily become a master. All you need to do is some serious, focused work on your play.
That 'chess is 99% tactics and blah-blah' thing is crap. Chess is several things (opening, endgame, middlegame strategy, positional play, tactics, psychology, time management...) which should be treated properly as a whole. getting just one element of lay and working exclusively on it is of very doubtful value, and at worst it may well turn out being a waste of time." - IM pfren (August 21, 2017)