Hands first: rinse, never soap
Everything about hand-feeding starts before your fingers reach the water. Rinse your hands thoroughly in plain water and dry them on a clean towel - soap residue, hand cream and sunscreen are all contaminants in a small tank, and a betta's mouth is about to touch your skin. Wet the fingertip you will feed from so the pellet rests on a damp surface rather than sticking to dry skin. If you prefer not to use a finger at all, feeding tweezers give the same closeness with a little distance, and many bettas accept them within a session or two.
Teach the cue before the treat
Bettas learn routines quickly, and trust builds faster when the routine is predictable. Pick one corner of the tank and one small signal - your hand appearing at that corner, or a soft tap on the rim, never a bang on the glass - and use it at the same time each day. For the first sessions, simply hold a single pellet at the surface and wait. A curious betta may take minutes to approach, or may flare at the strange object invading his water; both are fine. Let him close the distance himself every time. The lesson you are teaching is that the hand predicts food and never chases, grabs or corners him.
One pellet, full attention
Hold the pellet just at the surface, half in and half out of the water, so he can nip it cleanly from your fingertip. One pellet per approach, and only two or three approaches in a session: a betta's stomach is roughly the size of his eye, and the fastest way to ruin a trust ritual is to turn it into an all-you-can-eat. If a pellet sinks uneaten, fish it out rather than leaving it to foul the water, and end the session while he is still keen - tomorrow's eagerness is built by today's unfinished appetite. Once he is confident, vary the reward occasionally with a thawed frozen morsel held the same way.
Keep the ritual small and daily
Short, daily sessions beat long, occasional ones. Two minutes at the same hour becomes a fixture of his day, and you will see the change in stages: first he comes to the corner when he sees you, then he rises before the pellet appears, then he follows your finger along the glass. That progression is the trust you were after, and it has a practical dividend - a betta who comes to hand is easy to inspect up close, easy to tempt into a cup for tank work, and easy to feed precisely in a community tank where faster fish compete.
One routine, whoever is feeding
The ritual only stays a ritual if everyone follows it - the same corner, the same cue, the same two or three pellets, and no bonus feeds from a second person who did not know the first had been. That is where writing it down pays: listing the hand-feeding session among his Care Teams tasks in KinsLe, with the cue and portion noted, means a partner or sitter reproduces your routine exactly, the betta's trust in people in general keeps growing, and his waistline survives everyone's affection.