Hint: Bank Robbing
Not really a cheat but still a great way to get money easily. You'll need a Log Deleter version 4, A HUD Connection Analyzer, a Proxy Bypass version 5, a dictionary hacker is useful, and a rank of intermediate. Get a mission to trace a balance transfer. After you complete the mission to find out where the money went go back into the account and set up a transfer for the money to your bank account. You'll need to turn on the Proxy Bypass to finalize it. Then go into view statement and erase the log of the transfer (top one). Leave and immediately go to wherever you wipe your tracks at and do so. Then go into your bank account, bypass the proxy, delete the record in the statement saying you received the money, and leave and wipe your tracks again. This is an easy way to make hundreds of thousands of credits

Hint: No Evidence
You will first need a password breaker. Connect directly to InterNic, select admin and then crack the password (They will not trace you!). Then with a Lvl 4 or above Log Deleter, you can delete everything in the list (if any) to cover your tracks. In order for this to work you will have to re-route your connection through InterNic when doing missions. Preferably make it your third or fourth connection. Then once you've finished the mission follow the steps as above. Good Luck! It has helped me a lot!