When tinting have the lens and the film under a running tap. This stops small dust pieces and other contaminants getting under. Then using a bank card (or similar) peel back halfway and use the card to press back down, turn 180 and peel back halfway and use the card again. Should be better

Do you trim the tint first or after? I usually cut a square a bit oversize and cu after I installed it and wondered if that could Also introduce some bubbles because of the film manipulation 🤔