In order to avoid unsightly "Baby Crap" models finishes, Start with tamiya XF60 Dark Yellow. It's a decent colour, but I typically add lots of other shades to it, like Tamiya Flat White, and you can get good results with Tamiya Deck Tan, and sometimes I will add equal parts of Tamiya Flat White and Flat Yellow.
Adding pure flat yellow will help get the weird greenish tint out of the Tamiya Dark Yellow. There are lots of ways to skin this cat, but I have had good results with these colour mixes, and I do lighten quite a bit for scale effect. See my Stug IIIG in the gallery here, it was base coated in Dark Yellow, with equal parts flat white & flat yellow added.