I guess I have more to say.
A major concern of mine is that the weapons and ammo that I put in my maps are suitable for the level. During the construction of "The Gray Incident," I have realized that there are some weapons that are just inappropriate, and some weapons that kick ass through the whole game. This ends up being problematic - why would anyone use the SMG? There's hardly any underwater areas, and it burns ammo so fast that its strength (it is very powerful) is limited to just a few seconds. So what's the solution? Either don't put it in at all, or put in a lot of ammo. And even then, you could easily stick with the Assault Rifle and be fine.
So my advice on weapons and ammunition would be to keep in mind about what makes sense for the level. This is different for solo and netplay, obviously. In solo maps, cramped areas with lots of monsters would call on a shotgun, so it would be wise for the mapmaker to provide the shotgun (trust me, just because it's hard doesn't mean it's FUN). Unless there's a lot of Hunters, Cyborgs, or something like that, avoid providing an excess of fusion ammo, because it's a waste of time to use the fusion pistol on Troopers. If there's a lot of Enforcers on sniper ledges, offer the player extra pistol ammo, grenades, or even SMG ammo. Don't force the player to waste ammo by using the shotgun to snipe Enforcers from 15 WU away - that's not fun. Know what's appropriate. A common fault of mappers who want to make a level "hard" is to provide inadequate or inappropriate gear. This is more frustrating than hard - don't cap someone's skill like that.
As for netmaps, it's almost the other way around. Think about how ridiculously powerful the Shotgun is on small, crowded maps. Do you really want the battle to degenerate to skill-less, one-shot-kills because you can't avoid the crushing power of the Shotgun? If all you have are narrow hallways, maybe you should stick with the AR, or the fusion pistol (or fix your map, because it sucks). This isn't to say that you should not ever be able to exploit the terrain, but don't let it get out of hand. The SPNKR can be offset by having large open spaces - this is good! Counter the immense strength of the rocket launcher by allowing players to stay out of reach and harass them with the SMG. Nobody should be able to win a game by being a lamer and camping the battlefield with an awesome weapon that can't be beaten.
And that's just weapons. Keep ammo in mind, too. In single player, remember that if you provide almost no ammo for a weapon, it won't be used except as a panic button. This is a great way to prevent players from just cruising forward with the TOZT throughout the whole game. Provide plenty of ammo for the basic weapons (man, I absolutely loathe being starved on AR ammo), but feed smaller amounts of heavy ammo. Got a battle with a Major Juggernaut? Provide some SPNKR packs. The player can either choose to use them right away to deal a lot of damage to that Juggernaut... or they can hold on to it, and use it later on when it could kill off a lot of little monsters. Don't provide 80 SPNKR packs so they can do both.
The same principle applies to netmaps, sort of, except for one major difference: even if you do provide a weapon without ammo, it'll still be used quickly. Conservation does no good in netplay since death comes so quickly. If you want an example, look at Duality: there's two SPNKR packs on Duality, and both of them are not near the main arena. However, there's lots of SPNKRs, and they get used pretty quickly. If you don't want someone to abuse a weapon, hold out on ammo.
