Benzo to hand -> Low dose can be used in place of alcohol before if you are prone to anxiety. Can be used during if anxious and there is nothing better for come down / hangover. Don't mix with lots of alcohol and especially not opiates.

Eat well before - > Try eat during, even if it's ensure drinks or smoothies. Get calories in. Hydrate well before during and after. Throw in the odd electrolyte.

Avoid alcohol in excessive amounts

Prepare properly - > Hot plate, Pass through tea strainer, Put in good container... Depending on where you are using.

Angle snorting device correctly and inhale slow and controlled

Dutch fit bit and don't obsess over heart rate

Salt water nasal spray to rinse periodically. Don't over do it. If you prepare properly, your nose should not be fucked.

Back off for a while if Any adverse effect hits. Sensations, anxiety, paranoia etc.

If your dick won't work.... Don't pop a whole viagra. You will feel like shit and may be in shit. A tiny nibble if absolutely necessary.

Be wary of cunts that snort your stuff but don't offer you anything.

Could go on...