Typically, people learn two openings as black... one vs 1.e4 and one vs 1.d4.
The fact you mention the semi slav after 1.e4 just goes to show you're a beginner... which is fine. As long as you're brining your knights and bishops off the back rank, and castling, you'll be doing well in the opening... but calling 1.e4 c6 the semi slav is a bit silly.
By the way, the 100 year old wisdom is to learn endgames first. Middlegames (tactics and strategy) second, and openings last.
Capablanca was recommending this in the 1920s.
IOW if you're a relatively new player you shouldn't worry too much about openings.
By the way, the 100 year old wisdom is to learn endgames first. Middlegames (tactics and strategy) second, and openings last.
Capablanca was recommending this in the 1920s.
IOW if you're a relatively new player you shouldn't worry too much about openings.
+1
Forget about openings before 1500 at very least.
Learn opening and general chess principles instead.
Typically, people learn two openings as black... one vs 1.e4 and one vs 1.d4.
The fact you mention the semi slav after 1.e4 just goes to show you're a beginner... which is fine. As long as you're brining your knights and bishops off the back rank, and castling, you'll be doing well in the opening... but calling 1.e4 c6 the semi slav is a bit silly.
Beginner, I think sometimes is a misleading phrase. Only ever played casual chess (first game must have been played in the 80's), and there have been decades without games. But I found that I did ok. It was only when I joined chess.com I realised how erratic my play was and it was at this point I started to look at my weaknesses. And tbh I wasn't that bothered about openings, its just what people like Gotham Chess was saying...
Gotham chess is some no name IM who is capitalizing on the recent wave of new players to grow his YouTube channel.
He's not a total idiot when it comes to chess, but other than entertainment, I wouldn't ever recommend him to a new player.
It's nice that a non-GM is finding ways to make money off of chess (usually they struggle) but that's what it is, just some ridiculous young IM focused on clickbait more than anything.
Anyway, I guess when I bring up that stuff it isn't very useful.
You were saying in your original post it's nice to have an idea for what you'll do in the opening. I agree. If you want to play 1.e4 c6 as black and call it a semi slav, then whatever. As long as you're developing and castling it will be good 
You also brought up the idea of checking for your opponent's threats. I happened to have made a post about that. Maybe you'll find it useful.
https://www.chess.com/forum/view/for-beginners/the-most-important-concept-for-all-beginners
Anyway, I guess when I bring up that stuff it isn't very useful.
You were saying in your original post it's nice to have an idea for what you'll do in the opening. I agree. If you want to play 1.e4 c6 as black and call it a semi slav, then whatever. As long as you're developing and castling it will be good
You also brought up the idea of checking for your opponent's threats. I happened to have made a post about that. Maybe you'll find it useful.
https://www.chess.com/forum/view/for-beginners/the-most-important-concept-for-all-beginners
For me it's more heat of the moment and forgetting to evaluate what the position will be after the move. But now I'm aware of it, it's something for me to work on. Playing 10 min games at the moment and most are finished within the first few mins. So I have plenty of time for good habits, its just trying to make them happen.
Starting to play with the semi slav as my black defence. With white I am trying to go with the London system, but to me unless you can get the build order right, you are left with a lot of issues.
With the Semi Slav, although if you opponent plays E4, you cant really play d5 as your first move, this to me can be sorted by going c6 first and then d5 as a second move.
So to me the Semi Slav is a hell of a lot more flexible and is useable in a lot more games.
I still need to learn both properly, but I do think if you can at least have one white and one black opening, you are that little bit further on then trying to just use tactics from the get go.
Main failing, which I can't seem to shake is allowing the moves to flow automatically. The amount of times I realise after I have played a move, I didn't check opposing threats is getting embarrassing.