hard to say from what it depends, some ideas:
- check how many generals you have, remeber that in MOS you have all the 9 nazguls that costs you a lot already in terms of upkeep, so do not recruit more orc generals until you can really afford it. if it comes out that you have say 6-8 orc generals just keep the 2-3 best among them, send the rest alltogether in a stack attacking/harassing Gondor and use them for something good
- at which turn you are? at any rate the first turns for Mordor are quite hard on economic issues, you'll need to invest on the few improvements you can do (mostly mines)
- do not waste money in getting small villages, spare troops and Nazguls to crush Gondor and take their rich cities; for the rebels, look north-east between you and Ruhn, there are some towns there that might be worth to be conquered, but to turn your tide you need Gondor money, really.
- do not build any tanner or blacksmith, they are waste of money at this stage
can't say more now, perhaps if you let me know more I can help you better
