Father's Day is a special occasion to express love and gratitude to our fathers for all the sacrifices and hard work they have done for us. If you are looking for ways to say warm words to your father in English, here are some tips that can help you:

1. Start with a greeting: 'Happy Father's Day, Dad!' or 'Dear Dad, on this special day, I want to tell you how much I love and appreciate you.'

2. Express your gratitude: 'Thank you for always being there for me, for your unconditional love, and for all the sacrifices you made to give me a better life.'

3. Share a memory: 'I remember when you taught me how to ride a bike, and how patient you were when I fell down. Those are some of my fondest memories with you.'

4. Make a promise: 'I promise to always make you proud, to work hard and achieve my goals, and to be there for you when you need me.'

5. End with a heartfelt message: 'Thank you for being the best dad in the world. I love you more than words can express.'

Remember, it's not about the words you say, but the feelings behind them. Speak from your heart, and your father will feel your love and appreciation.