I think this thing of skill in games tends to be a little of too much pride and taking the game a bit more serious than it should.
In general I think it's best just to take a high risk once in a while if you think that 'luck' is not going your way; if you loose laugh about it and enjoy the game :)
Onto the house rules to modify results:
Die result for resources tend not to surprise much because you roll plenty of them; you may have a crazy roll once but if you complete the game it may have not decided it
The die results that have HUGE variance are the card rolls, where you roll N dice with N being the number of players. That's because you don't roll many of this (4 sets per game?)
For instance if you are 4 players one of you may buy this kind of cards two times in a row and roll 6,1,2,3 then 5,1,2,2.
Or better consider 6,5,1,2 and then 6,5,2,2
That seriously affects the game because one or two players get two tools or agriculture level in a row while the other players get one resource. In particular the second player in the later case gets an edge over the other two players for free! (the first player is the one who buys the card)
To lower the variance we have sometimes agreed that in 4 players game the person who buys the card rerolls if two pairs of the result have a difference of 3 or more:
If you roll 6,6,3,3 = reroll because = > 6 - 3 = 3 , 6 -3 = 3.
If you roll 6,6,3,4 = don't reroll because => 6 -3 = 3 , 6 -4 = 2.
6,5,1,2 = reroll => 6 - 2 = 4 , 5 -1 = 4.
That way the card MAY STILL be decisive, but with less likeliness.
But I have to say that for our games it's still a minor thing