Well, I'm a really aggressive player, I try to immediately go steal creeps and destroy enemy resource buildings and barracks asap. That's just me personally. It does all come down to what map and faction you are though. I can give some faction advice.
Gondor: Do not start with a signal fire, get farms and then get cavalry. Gondor cavalry will absolutely wreck anything mordor has except for the ungol halberdiers, and its great for creeping.
Rohan: This is the only matchup where peasant spam is not very efficient. Get cavalry asap, and you own the field.
Elves: Beornings, beornings, beornings.
Dwarves: Play as Iron Hills. The charge ability of the basic guardian combined with the debuff of ravens absolutely wreck basic orcs. Get Murin fast to kill enemy nazgul.
Isengard: I would call this matchup the most difficult of all factions. Wildmen spam isn't great, and is expensive compared to Mordors orc spam. However that's the only real choice you have, combined with your strong Bill Ferny. Get Wulfgar fast as well to kill nazgul, he's almost impossible to spot in the middle of some wildmen.
Besides that, general tips are avoid fighting enemy orcs and go straight for resource buildings, and target enemy heroes with your heroes while fighting. Mordor has a distinct disadvantage when it comes to heroes, they are all really unique and noticeable in the middle of armies, while most other factions heroes blend in with the troops quite well. Gorbag is the weakest scout hero in the game, and shagrat is even worse, so use that to your advantage. If you ever want to try it, try hitting the barracks asap, avoiding even creeping. If you destroy the barracks fast enough you will absolutely cripple the enemy. I will again restate that I do not think that a nerf is necessary for Mordor in their current form, you just have to have the knowledge to counter them. Although I do agree with making barricade a 3 point power, I think that it should be swapped in cost with the reinforcements of Rhun.