General tips/guides for campaign?

I bought AOE2 HD in the Steam sale and started playing the campaign. RTS games are not my primary "field" but I sometimes play them, including the original AOE decades ago.

Currently I'm at the "Age of Kings" campaign, mission "The Rising", and I kinda suck at it. Reading a "walkthrough" for this mission helped me, but still I have to repeatedly load a saved game because I lost all my units in a battle or the AI started a devastating counter-attack. Mostly I'm building lots of units (with a good combination of melee units, archers, scorpions) but as soon as I attack the opponent, I suffer heavy losses.

I believe I don't suck the economical, but the combat part. Maybe I'm just overwhelmed in combat and don't know how to act.

Now I don't want to read guides for every mission but be able to win them all by myself.

Anyone got any tips for me to be able to not suck so I can enjoy the game?

Thanks and a happy new year!