1 - Set up Region
As much of "silly" it may look like, setting up a region for your guild can save up alot of problems regarding kick, as we know the world has diff timezones and the such, there is a languague thing, while i strongly believe even the guild chat is capped per region, it's better to not join a russian guild if you are not or do not know how to speak russian (amrite?)
so set up the region/country in your thread title, like [Singapore] or [Europe]
2 - Activity
Hang on, read first, there is a Activity "quota" to specify in your guild IF you are the kind of player that has organization. for instance, set up a Weekly donation or no donations at all in the "body" of your thread, usually in Bold to highlight it, not all guilds charge weekly fees, but some players may not be interested in such things, or may, i dont know people...
3 - Level/Tiers Requirement
Yes, we know it shows up in the guild chart, but since here is a topic to guild recruitment, it's a great advice to put the minimal level requirement for the players to join a guild, or the minimal level you want a guild to have to join in, like [Level 100+] or [Master 1]. it can save up some time of people posting if the guild/player has preferences for level.
4 - Outside Game Chatting
As mentioned by Emera, you can also add a "Extra" app if you use it for clan chatting purposes. like Whatsapp or Kik, LINE and so on. be sure to mention IF you are using private-like or public rooms, your App Username (for Private Messages regarding recruitment) post the room name/password in case it's public/private (like i will do on a thread i will create as a example). that way you can use the game chatting for "outside reasons" like posting messages that either may be for a morale boost or anything like that.
well, that's all i can remember, you can also set up your global atk and def (the ones under your char) to see if a guild is willing to accept ya. there's some people that recruits using global values as a criteria, so [5,5 Nature atk, 4.7 Nature def]
yes, that pretty much cover all the things to make things clear for guilds criterias, they can save up alot of time, even when it may looks like they don't, peace.

dis be topic to inform plepe, not to guild recruitment exactly but to inform nonetheless