Mankind (and womankind and kidkind) has searched for an effective mosquito repellent since the beginning of time. Smearing mud on exposed skin is somewhat effective (and fun for the kids) but not very practical. Bear grease, used in the same manner, is reputed to work but is not really acceptable at pool parties.
Botanical extracts of lemon grass, citronella and other scented plants give only a fraction of the control that DEET (the active ingredient in many repellents) gives.
The citrosa “Mosquito Repellent Plant” does not work nor do ultrasonic mosquito repellers. The electric bug zappers you hang in the back yard attract and kill thousands more beneficial bugs than mosquitoes.
If you prefer not to use DEET (click for sources), your best bet is to use products containing oil of lemon eucalyptus (click for sources) or picaridin (click for sources). Both are very effective. Personally, the feel of picaridin spray on my skin is much less oily than DEET.
Another way to keep mosquitoes at bay on your deck or patio is to use an electric fan. A constant gentle breeze is more than most mosquitoes can fight.