I need advice on fusing materials.

I’m kinda new to Zelda, (got to last boss in botw and just started totk) 30 hours in and found 3 fairies.. I remember that lots of these monster materials will be needed for upgrades.. I’m now reluctant not to use my mats on fusing weapons for extra damage, I asked chatgpt which to use but they just said as long as I have 20+ mats I can use the rest for fusing but I’m not close to having that much..

Anyways, basically I’m looking for tips on which mats to use for fusing weapons early- mid game. Without ending up regretting it when I can’t upgrade my armor or whatever.