I’m trying to formulate the basics to improve my own game but also to give friends a general idea when I try to introduce them to the game so it will be more interesting for them. The following are the basics as far as I understand them:
First corners, then sides, then middle
Always look for the move with the highest potential on the whole board
Don’t defend groups that don’t need defending, but always keep your bases alive
Keep your stones connected
Don’t be afraid of sacrificing a couple of stones
Approach from the larger side
Approach the weakest groups
It is usually a good idea to hane two or three stones
When in doubt cut
Keep on the 3rd and 4th line in the beginning and try to push the opponent to the 2nd and 1st line
Are any of these principles not part of the basics and should any other be added?
At the opening phase, play on the 3rd line to make territory and on the 4th line to make influence
Corners, then sides, then center.
Urgent moves before big moves: if one of your groups is in danger, defend it. If one of your opponent’s groups has a weakness, attack it to make profit. If all groups on the board are strong, play a big point.
Keeping your stones connected is important in general, but is not always necessary if the two groups are already alive or can be defended separately without damage. Maybe more basic and important: count liberties during contact fights.
Sacrificing is a more difficult topic.You can sacrifice stones if they don’t affect the strength of the involved groups, but a beginner doesn’t always know which stones are important and which ones are not.
Cutting is also an even more difficult subject. You can cut and fight if you have enough “friends” around, otherwise cutting may be dangerous (unless you plan to sacrifice the cutting stones).
All that you said actually sounds pretty advanced.
When you introduce the game to friends, I recommend teaching them about liberties and not much more. Play on a 9x9 board, not a 19x19 board. And play a few games where the goal is just to capture stones, not even make territory.
Then you can move on to playing for territory, if they want to. At this point you still don’t need to explain about eyes, nor any strategy.
If they play too many moves on the first or second line you can explain why that’s too slow, although even that is probably not necessary, since they will probably notice that you avoid the first and second lines without you having to explain it.
Remember that go is a game. Following too many strategic rules is pointless if they don’t know why they’re following these rules.
I think this should not be considered a good rule of thumb.
Instead I suggest:
“Cut your opponents stones to initiate a fight that you expect to profit from. (For example if your opponents groups are vulnerable and your groups are strong, in the vicinity)”
Probably not basic though, as others already pointed out.