The Gold Mine has a little trick to it that most people don't know about.
The Gold Mine allows you to collect a little bit of gold each day from various Facebook friends who play GoW and gift you a little bit of Gold. For instance, at Lvl 1, you can collect 10 gold from 5 friends each day, allowing you to get 50 gold a day if 5 friends gift you gold. At Lvl 2 you can collect from 6 friends, etc., all the way up to Lvl 21, when you can collect from 25 friends. At lvl 21 you get a bonus 2 gold per person, so you can collect 300 gold a day.
It costs you 1,000 gold for each level up (Golden Pickaxe). I haven't done it yet, but you'll probably need a Master Hammer (2,000 gold) to lvl up from 20 to 21. That's 22,000 gold total to level up to a point where you get 300 gold a day. However, this trick (below) allows you to earn an additional 3k+ gold to offset the cost. That's over a ten day advantage until you make more gold than you put in.
Apparently when you start an upgrade, you can collect immediately at the new level, even if you've already collected that day. That means that if you do all 20 upgrades in a day, you can collect 21 times that day. You don't have to upgrade all levels in a single day to take advantage, just remember to collect before and after starting an upgrade.
Contributed by Geoponic
