Tips to pick up supply

I BF with my first but also supplemented just when needed.

I am trying to BF with lil one and while he took great and loves being on the boob now he is not getting enough. I have started giving him a little formula because after being on both boobs he cries and looks for more but nothing comes out. I want to pump and get my supply going. Any tips for getting it going? I just had him on the 21st so it's just taking off. Any food, snacks, drinks or pump long ideas y'all can help me with.