This Gondor build order was taught to me by Spartacus, and I used it a lot for my first games. It is solid, safe, and allows freedom to adapt to your enemy as the game progresses. I would recommend beginners to practise this build order exclusively until they can execute it as perfectly as possible. This build order also allows for early aggression and harassment.
Unit production in barracks: Gondor Soldier (s3), Gondor Pike (p1), Gondor Soldier (s4), Gondor Pike (p2)... (Keep production non-stop for as long as possible unless saving for cav). Adapt producing pikes or swords depending on your enemy. As a general rule, produce as few pikes as possible (they are less efficient than swords at everything except for protecting from cav), but have enough in case your enemy goes for cavalry. Usual ratios of pikes to swords can be 1:3 or 1:2. In extreme cases, can be 2:3 or even 1:1 (if your enemy goes for a lot of cav).
Unit actions: -Scout with Pippin (use scout ability near the enemy base). -s1: creep H1, harass F2e or creep/harass H3e. -s2: grab F1 & F2, creep H3, harass H1e (or H2e). -s3: creep H2 and troll with Pippin and p1. -p1: join s3 to creep troll. -p2: creep either W1 or W2. If there is early cavalry in the map, a possibility is to join some of the lone swords to protect them.
-At this point, you will likely have a decent force in the middle (Pippin, one or two swords and a pike), and some swords and pike(s) in the flanks, allowing you to control a big part of the map (via harassing or creeping more).
Buildings in base: -Barracks, Blacksmiths (in most match-ups, keep producing units from barracks, at some point your income will allow you to keep producing units AND get a blacksmith. It it better not to go for it before unless you have a good reason). -Other option for some match-ups (Gondor-Imladris, Gondor-Isengard, sometimes Gondor-Mordor) is to save up for a stable instead of spamming units or getting blacksmiths. In that case you might need to invest in one early pantry to have enough CP for the cavalry.