Removing the dying (yellow) leaves will help your buds. You can save and cure these leaves as they do have THC value. Once the plant enters flowering mode you need to focus on nutrients – buds love phosphorous so you can feed with a 10-30-10 mixture (nitrogen-phosphorous-potassium). You can boost with some extra potassium towards the end of the flowering cycle. Remember to keep the PH balanced throughout – ideally 6 for soil or just under for other mediums ( around 5.5). Nutrients aren’t absorbed properly if the PH is not balanced.