Good GMing

So, GMs, where do you get your ideas?  Actually that's not the question.  What is actually involved in running a good game?

I want to run a game, or more to the point, want to get some other people to play and the only way I'll manage is by running it myself.  Only thing is I have very little experience as a GM, and not a huge amount as a player, so I really don't know what's involved in making a game good.  Railroading is bad but is anything resembling railroading totally out of the question?  Is it a good idea to occasionally stick a signpost somewhere?  If the GM throws a problem in the way should he have some idea of how to solve it?  What should you do if the players suddenly decide that a piece of scenery is the key to the adventure? How do you balance difficulty?  What do you do if the players are not proactive enough?

A lot of you guys are roleplayers so what do you think works and doesn't? 

Pork!

Decided to buy some pork last weekend. So far I've had roast pork, Leftover pork and chips, and a pork stir fry. This leaves me with about one meal's worth of pork leftover. And on the subject of pork - crackling. I had a theory that if I got the skin nice and dry it would crisp up nicely. So I Dried it with paper towels and then rubbed it with some salt, then rubbed as much of the salt off as I could. It did indeed come out delightfully crispy. Also a bit salty though. Will have to try again.