The advanced skills involve some logical thinking, for example:
Looking at the number 2 alone, there are three cases:
But the number 1 shows that the third case is impossible, and therefore there are two cases left:
For both cases, the leftmost tile contains a mine, and therefore you can be sure that the first tile contains a mine:
Another way of thinking is that if the first tile does not contain a mine, then the remaining two tiles must contain mines. But this is impossible as the number 1 will be violated. Therefore you can conclude that the leftmost block must contain a mine.
Moving on, the number 2 shows that the circled tiles contain only one mine:
So the mine corresponding to the number 1 must be one of the two circled tiles, and so the remaining tile must be safe: