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

• denigrating
• denigration
• denigrative
• denigrator
• denigratory
• denim
• Denis Diderot
• Denisonia
• Denisonia superba
• denitrification
• denitrify
• denizen
• Denmark
• Denmark Vesey
• Dennis Gabor
• Dennstaedtia
• Dennstaedtia punctilobula
• Dennstaedtiaceae
• healthier
• healthily
• healthiness
• healthy
• heap
• heap up
• heaps