Cocaine
If you are using cocaine, use with people you know and trust.
Use a clean straw to snort if possible, and do not share straws to avoid spreading infections. If this is not possible sterilise the equipment you are using.
Cut up the powder as fine as possible to avoid taking more than you think
Alternate nostrils to lessen damage
Remember to start low and go slow; space time between each time you take some
Avoid mixing with other drugs, including alcohol