There are a few dangers associated with snorting.. most obvious being the "hole in septum" or septal perforation caused by long term snorting, where you develop a hole in the dividing part of your nose due to necrosis (death of tissue). The risk is much, much higher with something like cocaine as it is a vasoconstrictor, meaning it causes a reduced blood supply to the septum, but I think you can get it from snoring irritant drugs too - can't find any info at this time in the morning sorry!
I think the only way to minimise the risk of this is not to snort vasoconstricting drugs too often and not for too long periods of time, to give your nose a chance to recover. You could try nasal douching (inhaling small amounts of water or saline) to stop the drug accumulating on the inside of your nose - got no evidence that this works but it might be worth a try - but once the drug has entered your bloodstream the vasoconstriction is going to happen. Might help damage from irritation though.
In terms of infection - in theory you can transmit blood-bourne infections via shared snorting tubes, especially Hep C as it only needs a very tiny amount of blood, and nose-bleeds are not uncommon amongst drug-snorting peeps - but I can't find any cases where this actually happened. Shall have another look later. I much prefer not sharing a snorting tube, especially if it is a note. You could definitely catch a cold or sinusitits from insufflating viruses/bacteria and I'd rather not risk catching anything else! Carrying around your own straw or something would be the best way to minimise harm here
Nosebleeds can happen - I've had one after snorting some ketamine cut with something - nose started to bleed before I'd even finished my line! Horrible. So - try as much as you can to buy drugs from trusted sources, I guess, but be aware you will never 100% know what you are putting up your nose. People also typically get nosebleeds after long sessions snorting drugs that irritate your nose. Nosebleeds are much more likely when the lining of your nose is dry, as the tissues are more prone to damage then, so saline douches between lines might help here. You can also get nasal sprays but some of them can actually be quite irritating to your nose, especially if it is alread slightly damaged from snorting something. If you do get a nosebleed, try not to snort anything for at least a couple of weeks, to allow your nose to heal itself, and try to reduce the length and frequency of snorting sessions in future I guess!
Hmm can't think of anything else right now (only just woke up!) - shall pop back later if I do.
Overall snorting is a lot less dangerous than injecting, in terms of risk of infection and potential to damage your body, but there are a few risks and some sensible things you can do to minimise them
