NR's my favorite faction to play AoW with, mainly because I like the RP idea of taking down the various Imperial leaders.
While it might seem like they have a weak start, in actuality they have an incredibly potent one due to the warlords not having AI and therefore not doing any building. There are a number of planets near the top-right of the map, north of Yavin and Mon Cal, that have high credit bonuses and a large number of building spots (the chain from Telos to Ession). Playing smart, your starting units at Mon Cal and nearby planets should be sufficient to conquer these, and since the NR doesn't have a limit on how many mining facilities it can build per planet... within a few weeks IG you should easily have an income of several thousand, at which point you can just start spamming. Leave the rest of Zsinj's territory alone early on - Dathomir and the Iron Fist fleet over it can serve as a buffer zone against the real powers while you let the credits start rolling in as mines get built. Also, the PA's AI doesn't work in AoW, so a lot of their worlds are ripe for plundering once you get going, though it'll bring you into earlier fighting with the EotH, which seems to like expanding that way too.
Defensively, the IR seems to like to attack the NR's galactic core holdings first (Noquivzor, Ithor, etc.). My recommendation is actually to hold a ground defense of these planets - retreat any ships you can from the space attack and save them for when they'll be actually useful, build a light factory, spurt out a few T2bs and air speeders (especially air speeders, since the factories make T2bs mid-fight), and rush the enemy as they land with the vehicles while infantry secure turret points. Speeders can be brutal garrison units, since they are fast enough to reach landing zones before lots of units can come in and hit hard enough to wreck landing troops often before they can even shoot back. A rush of air speeders and T2bs has held off massive IR attacks for me multiple times, especially since they don't start with much in the way of advanced ground units. Various other worlds at choke points should be buffed in this direction early on also - a light factory and two or three speeder units at Garos IV (easy to take if you hit it early), Abregado Rae, Commenor and Duro can go a long way to stopping the IR's advance for relatively little money. However, I must warn that this tactic DOES require a good bit of micromanagement during the ground battles, particularly with air speeders/Vwings benefiting greatly if you give them a decent firing run rather than letting them circle, and auto-resolve will never be your friend.
Offensively, I focus on taking out the handful of IR planets in the south that are already mostly behind NR lines, Gyndine being high-priority due to the 3-tier shipyard and lots of building slots. Thyferra I often leave mostly alone until after Isard dies, since it then loses the hero units that make up half it's starting forces.
I try to have at least three "main" fleets... one's defending Fondor and my other south-middle planets, another's defending Mon Cal and slowly expanding in that corner, and another goes around the east of the map from Bothawui to the Maw, Kessel, and up until I link up my territories - effectively consolidating my control of the Outer Rim while I let the IR and EotH duke it out. Then I push up into Corellia and Kuat, or down through Myrkyr and Wayland.
The NR's a fair bit harder in Essence of War simply because the map is smaller, which makes the PA and IR's SSDs relatively bigger players on the field - in AoW you've got a lot more room to maneuver around them if your fleet's not ready to take them out yet. Plus, the PA's got active AI in Essence. Still, the ground defense strategy has yet to fail me as the NR. Even if eventually you lose the planet, it likely won't be to the first invasion or two made of starting units, and those losses will cost your enemies in time and resources they could've used to expand elsewhere. Overall, I don't find them weak at all. They don't start off with a huge military, sure, but you've got plenty of territory, the IR starts off in the middle of everybody and both the PA and EotH have crap home economies and must expand fast or quickly be left behind - if you ask me, it's pretty well balanced.
P.S. All of the above is my opinion after having beaten both Essence and Art of War as the NR on Admiral, in case that's relevant.