From where you are presently, keep walking around and battle a lot of enemies. If you are in Ms. Million's bag, you can get about 400 Zenny in each battle. You can also get 10,000 Zenny from doing the love letter job and from Ms. Millions.

In the Undernet 5 are three Green Mystery Datas. Save in front of them, then move the pointer in one direction to receive 100 Zenny, a virus, or 50,000 Zenny in each one of the three Green Mystery Datas.

Make sure you have Untrap. Go to Undernet 5. There will be three mystery program data. Use the Sub-chip Untrap and walk up to one of the mystery data. Unlock it. It will more than likely say "You got 100 Zenny!". Find the other one. It will usually have the same message. Find the last one. It will say "You got 50,000 Zenny!". Then, jack out and do it again. You can only do this a total of seven times; save it for when you need it.