Your first priority isn't iron, it's turnips, the yellow flowers. On the plus side, turnips can spawn in any swamp, even the small ones. On the minus side, they're rare, so finding them is very dependent on RNG. Obviously, they don't grow in water, so look around what little high ground you can find. If you're lucky it will be on the edge of the biome. Once you find one, do a happy dance, quietly, and get the heck out of there. Go home and farm them up until you have enough to upgrade your food. That will greatly increase your survivability.

Use campfires to suppress spawns in areas you're already cleared. They're also good for marking your path. They don't have to stay lit, and probably won't.

Mace is good for blobs and skellies, but the draugr are more likely to end your day. (Provided you are using your poison resist.) Use the bow any time you can. Otherwise the atgeir works great for staggering enemies and keeping them from hitting you. Normal draugr are easy with the atgeir.

Don't go at night. This is repeated often for good reason. You can ignore that advice after you are geared up, know what you are doing, and need to hunt wraiths for chains. Believe it or not, the swamp will seem easy by then.

Spawners are also hidden in stone ruins. Don't go in there. The buzzing fly noise is a warning. That is one of the worst places in the game to leave your tombstone.