I watched the 1vs1 on west emnet vs Ring, the most important thing for you to remember is BfME is all about harassment and economy, not who can pick the best army to counter your opponents like a CnC game. So sitting back at any point and building no army is even worse than it normally is in a CnC game, you should constantly be harassing his settlements and building units to defend the map.
Early game you always need extra uruks in 1vs1, so good idea starting with a pit. Your options are really either pit and 2 mills (the advantage being a stronger economy... provided you don't loose a mill) or pit furn and one forward mill (advantage being you catch his starting units earlier - if he's rushing ofc which Ring didn't but should have done). Vs Rohan though I'd say you can get away with pit 2 mills as they haven't got the advantage of placing land on your mill, so with chant and some labourers repairing it you should be able to save your mills. Send labourers to grab your other 2 mills. Make sure you send your first uruk forwards as soon as you're done claiming mills though, and find his peasants! Don't wait next to your base. In general, never have idle units, especially early game. After you've dealt with his first peasants, and any extra peasants he decides to make (scout for this, send some labs to key points so you spot them early enough) you should aim to get 5 uruks early game. Scout out his base so you know what he's building. If he gets a stable after 2 inside farms, be worried. Get a total of 5 uruks (4 extra, to make your pit level 2) to harass his farms with chant and take a creep or two with any extra uruks (just attack the lair, not the goblins and take the cash) and afterwards progress to pikes to defend your mills from horse and attack his, start to build up an economy ect. making sure you have enough pikes to cover all mills. Then buy an armoury when you get the cash, get all upgrades except for fire arrows, sell the armoury for a warg pit and get some wargs out. Your army vs a decent rohan will consist of mainly wargs and pikes, lurtz, and later saru and maybe 2 combos (2 is max). The only time you need more is if he spams Rohirim archers, but even then don't get pike combos, normal uruk/xbow combos are better. Once you get rain vs Rohan its an easy ride.
As I said this is all provided you scout fast stable build. If you see any other strat such as fast archers, any kind of hero spam, fast spearmen, there's no need to worry. Just kill all his farms and make mills there. You probably won't need 5 uruks to do this, so when you think you have enough switch to xbows and use them to creep the entire map, killing the lairs first so the creeps don't attack the xbows. I usually get a lot of xbows to do this with, maybe even 6+. Keep an eye on what he's doing because if he gets some horse like ring did you need to get some pikes. Your economy will be through the roof though as furns only cost you 240, so you can build up your base super fast. If he goes for heroes go for Lurtz and a couple of pikes, use pin and WC and the horse heroes die in seconds. More powerful heroes like lego you need to get ups first. Get ups then an outpost next to his base and a few battering rams and hit his base with some fully uppued uruks and pikes with warchant.
If that helped you in anyway I'd be happy to comment on any future games you post as well