* Make sure you wear technical, wicking material - anything not specifically designed for running will rub, and will hurt.
* Don't start longer runs in brand new clothes, they will rub, and it will hurt ('longer' = over 8 miles in my personal experience). Break new clothes in slowly, as you might for shoes.
* Don't skimp on socks. Buy good quality twin-skinned ones to prevent blisters.
* Vaseline. Lots of it.
* Gents : plasters on nipples, well-fitting pants. Those are areas you really don't want chafing, right? There's a good article on 'crotch chafing' here!
* Hot showers really hurt on rubbed bits. But it does help. So man up.
* Don't eat just before running (obvious, right? So why do so many people do it?).
* Don't have fizzy drinks just before either - not only will this make you potentially chuck up, it can also give you stitch.
* Don't try anything new (gels, jellybabies) on longer runs. Again, obvious, but I've seen this a lot.
* Don't 'glug' water while out on your run, or you will simply chuck it straight back up again. Sip, often.
* Stay hydrated. Drink plenty before and after running. This helps with all of the icky bits...
* Sometimes, simply going too hard or too fast will result in your body protesting with a quick vom. Listen.
* Go to the loo before you go running. Twice. And then once more, just to be sure....
* Plan routes to have loo stops at about 5k. If you make it past that, chances are you'll make it to the end.
* Take loo paper and a plastic bag. In an emergency, you can normally find dog poo bins to leave any (ahem) deposits.
* If you do need to 'go', make sure you check very carefully where you plan to use, even when apparently in the middle of nowhere - when having a sneaky mid-run emergency wee I once accidentally exposed myself to the (very full) Penzance to Paddington train somewhere near Bristol <blush>.
* Dogs have a habit of creeping up on you unexpectedly and sticking their nose anywhere they think is interesting. I'll leave *that* story for another day....
* Imodium works.
* The feeling that you need to go doesn't disappear so don't try and run through it - you won't like the outcome....