Leveling crafting whilst leveling DoW/DoM classes

[HEC]

Leveling a single craft class without support of other classes (gathering as well as crafting) is fairly hard and IMO not worth the effort if you don't have time or really enjoy it. The higher you'll get the more difficult it gets and not only due to the dependence of the gathered mats and crafted parts from other classes but also due to the need of the cross-class skills to be able to craft the high level recipies. I've actually fully leveled all my DoHs and DoLs prior reaching 50 at my first DoM / DoW class as I've really enjoyed it so much but that might not be the case for you as it's pretty time consuming but the resulting independence and self-suffiency is great - especially now with improved self repair system.

[Wulfyn]

You will have leve quests ( of course you would have to have done the battlecraft ones first) and guild quests from a npc in the adventurers guilds to help with leveling.

[Kydi]

Thanks everyone. Looks like I'll level my THM whilst gathering skins for leatherwork and mining then.

[Urthdigger]

Honestly, if you're going to craft as you level, you'll want to level all DoH/DoL together. You can share gear between all crafters and between all gatherers, and having them all together means not really having to purchase things off the market boards. I also highly recommend having a battle retainer and fishing retainer, as those are the hardest to get items for reliably.

[Niwashi]

How can I level crafts without making myself bankrupt, or do I need to level gathering and other crafts too so I can supply myself with materials?

I think you answered your own question there. You can either do it the expensive way or the time-consuming way. Most people who really get into crafting opt for the time consuming way of leveling all (or most) of the crafting/gathering classes together.

Other shortcuts that can help include knowing what materials you can get from NPCs (some things can be bought from very specific locations - and only specific locations!)

The Libra Eorzea app is good for checking these.

using crafting levequests to maximize your experience-per-craft (and get some rewards back), etc.

And the supply/provision missions from your GC. They're limited to once a day, but they give a huge XP boost (as well as GC seals). Even up into the upper 20's and low 30's, I can still gain a level every couple turn-ins or so just from supply missions alone.

Are there particular gathering/crafting skills that would complement armourer?

Leatherworker would be good for supporting armourer, but then you'll find leatherworker itself needs support from weaver, etc. All six of the main gear-focused crafting classes end up being co-dependent on each other for materials. Culinarian and alchemist stand apart as somewhat less necessary in that regard. (You may still need an occasional item from ALC, but not often.) But they provide good cross-class skills useful to other crafting classes. (At level 15, those are Hasty Touch from CUL and Tricks of the Trade from ALC, both of which help at dealing with a shortage of Crafting Points common while leveling up any crafting class.)