[Agema]

My tactics...

1) Site searching

Particularly with multipath mages, site searching is a great idea. If you've got 3+ magic paths at 2+ skill, you'll get 3 searches every 2 turns. That makes it both faster and much cheaper in gems than spells. You'll miss some sites with only level 2, but you'll get the vast majority. You can then do some spells afterwards to pick up spares if you think you need to. If you have multipath mages but several paths are only skill level 1, I'd send them out searching as above for a quick income boost, but you need to go round later with spells as otherwise you'll miss plenty. Another thing to consider is that multipath mages tend to be expensive, rare, and often fragile. Into the midgame, you might not want them wandering around as they can be too easily killed.

2) Spell searching

If you only have 2-path mages searching is much less attractive except as an early-game boost. (And when I say 2-path, I mean both paths at skill level 2 minimum.) Switch to spells ASAP. Any paths you can only get level 1 in you'll have to site search anyway, unless you trade for skill boosters.

In water, Voice of Tiamat is a no-brainer, definitely use as soon as possible. It's still 2 gems / path, but it saves a lot of time. Be aware Dark Knowledge costs 3 gems rather than the conventional 2, so gets that little bit more expensive.

I don't like Acashic record much. I just think it's too expensive for general use. There are two "best" times to use it. Terrains that tend to have more sites (wasteland, mountains) is one - don't use it on farmland unless... The other is when you can see some places have a site by the province scales as they increase heat or death or whatever: if you don't think you've got the right path to find it, Acashic Record is the answer.