Before exploring the hidden maps, get a Bigboy, Vengence or Goliath ship. Go to map X-4. Go through the jumpgate in between two other ones. Then go through the center jumpgate. You cannot see it on the map that appears after you jump. You will now be in a hidden map. Be careful because the jumpgates here do not offer protection.
Saving uridium
Do not upgrade your starting ship. Stay with the Phoenix for awhile. Spend 500 uridium to get a Cloak Type I at the Hangar. Take all the mining quests first and save your credits. Offload your raw ore regularly when you run out of cargo space. Save the mining quest that requires you to harvest 300 ore in 10 minutes for last. If your ship is destroyed, your next one is free as long as you do not upgrade it. You will not lose any equipment, experience, ore, or uridium to replace your lost ship.