Nicole,
My first choice for liquid resin colorants are to use those specifically designed for resin. Resin hates moisture, so I try to make sure to use those that should get along with the resin.
We have colorants designed for resin in our store here: https://shop.resinobsession.com/collections/colorants
If you want to try other things to color your resin, try to use as little as possible so as not to impact the resin curing.