Banana yellow is more yellow than chartreuse. I think it would be easier just to start with bright yellow but I'll take a shot with your chartreuse.
I'd start with about 15 drops to 4 oz to opaque it a little. Make your basic charatreuse from raw plastic and cook, then while hot make your color adjustments. Start with 1 drop of white in the hot chartreuse to help stop light from penetrating the bright color, which makes it want to glow.
I'd use a very thin stick...toothpick diameter....and dip it in a dark brown or black just far enough to put a miniscule drop on the end and blend it in. You may have to do this a few times but BABY steps here is the key so mix in each dipped stick before doing another. Myself I'd lean towards the brown as a toning color since its more on the yellow end than black is. Keep some white handy to use in the same way to make any lighter adjustments.
When I am matching colors I use bamboo skewers used for cooking. These are tooth pick diameter and sharply pointed on one end which is the end I use as a color pick-up.
Personally I think you'd be steps ahead by starting with a yellow, not chartreuse. Chartreuse has uv enhancers in it that focus uv light inward and make it light up and those enhancers will fight you. Basic yellow won't do that. Basic yellow with a small dip of brown would give you your banana color in a blink. Once you're there you could always add a small drop of chartreuse to give your basic color some zip.
