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

• semi-dry
• semi-erect
• semi-evergreen
• semi-processed
• semi-prostrate
• semi-retired
• semi-skimmed milk
• semi-sweet chocolate
• semi-tuberous
• semi-upright
• towage
• toward
• towards
• towboat
• towel
• towel bar
• towel horse
• towel rack
• towel rail
• towel ring
• towelette
• toweling
• towelling
• tower
• tower block