1. One thing at a time
   - in small stages, piecemeal, step-by-step, stepwise

1. A little bit at a time
   - piecemeal, little by little, in stages 
2. In a gradual manner
   - gradually, step by step

See also: gradual

• bottle-nosed dolphin
• bottle-nosed whale
• bottle-shaped
• bottle-tree
• bottlebrush
• bottlebrush buckeye
• bottlecap
• bottled gas
• bottled water
• bottlefeed
• bottleful
• bottleneck
• bottlenose
• bottlenose dolphin
• bottlenose whale
• bottler
• bottling plant
• bottom
• bottom dog
• bottom fermentation
• bottom fermenting yeast
• bottom fish
• bottom line
• bottom lurkers
• bottom of the inning