Tooth Colour is naturally straw yellow in colour. If you feel its visibly yellowish, you should go toh the nearest dentist, and get yourself a complete oral prophylaxis done. Scaling and polishing does help, if the stain is external. In case of internal staining z it might require further treatment like teeth whitening, but that can only be recommended after visualisation of your teeth.
Next Steps
go for oral prophylaxis once.
after that you can use snow dent toothpaste, for 2 months, using a pea size, every alternate days.
follow up with your dentist.