My family is moving in...how do i increase hot water availability?

Type of water heater is not known.
Gas or electric, tank or tankless?

1) Tank: With tank-type gas and electric heaters, turn up thermostat on heater, and keep sediment out of tank by flushing each 6 months.
http://waterheatertimer.org/How-to-adjust-water-heater-temperature.html
http://waterheatertimer.org/Clean-sediment-out-of-water-heater.html
I do not recommend tankless for the budget conscious consumer, because of cost and potential problems.Tankless water heaters have risk of failure when water heater temperature is increased.
Tankless require continual maintenance, and are expensive to repair.

2) Tank: Install larger tank-type water heater with more gallons of storage. Plan ahead before purchase and get coupons that apply to purchase.
http://waterheatertimer.org/How-to-install-gas-water-heater.html
See size chart:
http://waterheatertimer.org/images/Small-water-heater.jpg
Tankless: Larger capacity tankless unit will consume a lot of fuel and might require larger gas line, and increased water flow, etc.

3) Tank-type water heater: Insulate tank, install heat trap pipes, wrap pipes with insulation, install tempering tank, install low-flow shower heads, use shower timer, fix water leaks, keep tank free of sediment, use single-handle faucet correctly, check anode rod, check for leaks on regular basis etc
http://waterheatertimer.org/9-ways-to-save-with-water-heater.html

4) Take showers instead of baths.
Shower uses 5-9 gallons hot water. Bath 12-15 gallons hot water.

5) Tank-type: Install tank-type water heater with higher recovery rating, and larger first-hour delivery.
Typical electric water heater heats 21 gallons per hour. Typical gas 41 gallons per hour.
High recovery gas can produce 80-100 gallons per hour.
These units consume more fuel per hour of operation, and are generally more expensive up front, and will require larger gas line.
Buy at local plumbing supply.

6) Electric tank-type: add additional 240Volt electric line to water heater and wire elements for simultaneous operation. Add a comment with details about your electrical questions if you want to do this. Hot water delivery capacity of regular tank can be increased 15%-30%, from 21 gallons per hour to 25+ gallons per hour.

7) Add a comment for more help.

8) Take a moment and rate answer for accuracy:
And take advantage of fixya expert assistance live.
For a price, expert works with you while you work on water heater or any do-it-yourself project.
Fixya is always less expensive than a service call.

Large water heater, turn p the themo stat to a higher setting ( watch for burns with young childern and older folks)

or the best install a tempering valve. this valve mixs hot water with cold water before it goes into the building.

Again if you have young ones or old people they can burn faster than any other group.the best is a larger heater for the DIY person.

Thanks Tom