Around the Home/Office: 
1. Replace incandescent bulbs with LED's
2. Turn lights off in rooms not being used
3. Use timers on lights
4. Install dimmer switches
5. Re-seal / caulk windows
6. Install storm windows
7. Replace older windows with high-performance windows
8. Re-seal doors around the frame and the bottom
9. Replace older or damaged doors
10. Add insulation in attics and crawl spaces that border the outside
11. Repair any roof damage
12. Repair any exterior wall damage/add insulation
13. Plant trees for shade
14. Plant short dense shrubs close to foundation to insulate against cold
15. Install roof or cover on outside deck
16. Install solar panels
17. Install a wind turbine
18. Cover bare floors for heat retention
19. Install an energy-efficient heat pump
20. For winter, set thermostat to 68-70 degrees during the day and reduce it to 65-68 degrees at night
21. For Summer, set thermostat to 72-75 degrees during the day and increase to 76-78 degrees at night
22. Open windows at night to capture the cool summer breeze
23. Place fans in windows on cooler summer days instead of using the A/C
24. Lower thermostat in winter and raise it in summer when leaving the house
25. Avoid heating or cooling unused areas and rooms
26. Avoid overheating or cooling your home
27. Replace furnace and A/C filters regularly
28. Give A/C a tune up
29. Repair leaky ducts
30. Keep furniture, carpeting, and curtains from blocking registers and return ducts
31. Use shades, blinds, and drapes in summer to block the sun
32. Use/install ceiling fans
33. Close fireplace damper when not being used
34. Try not to use the fireplace and central heating at the same time
35. Turn off fireplace pilot during the summer
36. Keep garage door closed, especially in winter
Regarding Appliances:
37. Discontinue using portable electric heaters
38. Replace older and damaged appliances with Energy Star rated appliances
39. Repair refrigerator door seals
40. Avoid opening refrigerator/freezer doors to browse
41. Let hot foods cool before placing in refrigerator/freezer
42. Clean the back of refrigerator regularly
43. Unplug extra refrigerator and/or freezer located in hot garage or utility room
44. Keep freezer full as it uses less energy than an empty one
45. Unplug phone charger when not in use
46. Unplug appliances not in use such as coffee maker, toaster, microwave, etc.
47. Use microwave or toaster oven to re-heat food instead of full-sized oven
48. Use a power strip for electronics that can be easily turned off when not in use
49. Turn off computer or use sleep mode
50. Fill up dishwasher before running
51. Turn off dishwasher heated dry setting and open door to air dry
52. Wash and dry only full loads of clothes
53. Wash clothes with cold water
54. Vent dryer to the outside
55. Avoid over drying clothes
56. Hang clothes to air dry
57. Grill out instead of cooking on the stove and/or oven
58. Only run kitchen and bathroom fans as long as necessary
59. Check hot water pipes for leaks
60. Turn off water heater when going on vacation
61. Install a solar water heater
62. Wrap insulation around water heater
63. Reduce water heater temperature setting to 120 degrees
64. Install a water heater timer
65. Turn off humidifier or dehumidifier when no longer needed
66. Keep generator (if applicable) well-tuned to be prepared for possible power outages
Water: 
67. Install a rain barrel to collect rainwater for plant watering
68. Take shorter showers
69. Take a shower instead of a bath, uses less hot water
70. Capture cold water when running tap for warm or hot water, and re-use (plant watering, coffee maker, etc.)
71. Install a low-flow shower head
72. Turn water off while brushing teeth
73. Check faucets and toilets for leaks
74. Flush toilet every other time (with liquid waste)
75. Make sure toilet handle doesn't stick after flushing
76. Avoid overwatering with sprinkler system
77. Water garden and/or yard early morning or late afternoon to avoid high evaporation
78. Landscape with drought tolerant plants
79. Mulch around plants to help conserve water
80. Utilize spring for irrigation on property (if applicable)
81. Minimize vehicle washing
Vehicles and Transportation:
82. A properly tuned and oiled vehicle with correct tire pressure will get better mileage per gallon
83. Trade in gas vehicle for an electric or hybrid vehicle
84. Ride a bike
85. Walk instead of driving
86. Ride a scooter
87. Carpool or rideshare
88. Use public transportation
89. Telecommute if possible
90. Try a stay-cation instead of traveling for a vacation
91. Shop local and online
92. Park in central location for errands and walk to each stop
Miscellaneous:
93. Wear season/weather appropriate clothing
94. Wear clothing a second time
95. Sleep with an extra blanket for warmth
96. Dine by candlelight
97. Retire to bed 30 minutes earlier and turn off lights
98. Turn off the TV and play games, tell stories, play instruments, etc.
99. Walk/run outside or at the mall instead of using an electric treadmill
100. Use rechargeable batteries instead of disposable ones
101. Use cloth towels and napkins instead of disposable ones
102. Purchase fruits & vegetables loose instead of using a plastic bag
103. Bring reusable bags to the grocery store
104. Mend and repair clothing instead of replacing and discarding