The easiest is to change the lines at the top;
Guild woodsmens_guild
building guild_woodsmens_guild
levels 100 250 500
This determains the points needed to get the guild by level
level 1; 100
level 2; 250
level 3; 500

So if you were to lower these numbers to say;
Guild woodsmens_guild
building guild_woodsmens_guild
levels 50 125 250
It would litterally be twicw as easy to get the quild and increas it's level.