Another option is to use your NPC. As a DD job, a leveled Soothing Healer NPC is a great thing to have. I've become somewhat addicted to Campaign and have used my NPC to keep my weapon / magic skills capped whenever I get a level. The mobs you target will depend on your NPC's level (as well as your weapon skill level) but I generally target Even Match to low-Tough mobs.
For instance, in my early sixties, I went after Robber Crabs in Kuftal Tunnel (along with half of the rest of the server). Once those crabs got to be too weak and stopped giving consistent skillups, I went after their tougher cousins in the Boyahda Tree. Once those got to be too weak, things got a little more interesting (Steelshells are great skillup mobs, but there's a pretty big level gap between those crabs and the Robber Crabs). I ended up finding a nice little camp in the Meriphataud Mountains [S] with two speedy Raptor spawns. Raptors are a bit more problematic than crabs, to be sure, but they're still not bad NPC-leveling targets.
Obviously, if your weapon skill levels are close to capped, the gold standard for skilling up is a normal (non-Level Synced) party. If they're not, your best bet is a standard "safety-in-numbers" skillup party. Still, if you enjoy soloing and a little bit of a challenge, pushing the envelope with your NPC adventuring fellow is a good way to keep your skills capped. It's also a great way to level your NPC if it's not already leveled -- and having a leveled NPC is handy for so many reasons.
Plus, you get to keep all of the drops. All of the Beastmen's / Kindred's Seals and H.Q. Crab Shells are yours. The skins dropped by the raptors are going for 30K/stack on Garuda (and they have a better drop rate on the higher-level ones than their lower-level cousins in the present day). And if you pop an Empress Band before you start, you can even get a non-trivial chunk of EXP for your troubles, though of course the EXP you'll get pales in comparison to what you would get in a good party (or even in Campaign, for that matter).
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Vana'diel Bestiary is a great tool for finding mobs to skill up on. Enter your job, level, and current skill, and it will suggest mobs to target. If you want to go the NPC route, it may suggest mobs that are a bit too difficult for you to solo, so use the "Standard Exp Mob Search" and look for mobs that are DC-T to you.