Without knowing more details, I would ensure the following:
- Use a DOCSIS 3.0 modem that supports as much channel bonding as supported by your ISP.
- If your devices support gigabit, use a CAT6 ethernet cable for the connection. (e.g., modem to router, router to nas, router to desktop, etc.).
- Whatever 802.11 flavor your devices support, ensure you are using the least crowded channel in the area, and if the crowding in your area is minimal, enable wide channels for more bandwidth.
- Try to place the wifi router as close to center of your household as possible, and away from any walls or large metal objects if possible.
- If possible and practical, run an ethernet cable to devices that don't move often (e.g., run one ethernet cable to your entertainment center, to a switch, which you can connect your to your roku / appletv / firetv / smarttv / xbox / playstation / whatever).
- Use opendns on your router, and dnscrypt if supported, to ensure faster and secure dns lookups.