[i] Hmm! My best advice..

Pre-plan but don't plan TOO much. Plot out things but don't plot TOO much.
Because roleplaying is almost like a group weaving of stories- you can't always predict what is going to happen next, and sometimes those things change the entire course of a roleplay.

I think the best way to keep a roleplay active and entertaining is just like improv acting. Never say no, and always take what is happening and run with it. Sure you can turn it around back into the place you want it to go..but you should take 5 minutes and think about what another character has brought to the table- and it can change your whole perspective of the roleplay.

Though my roleplays have never lasted very long, people always comment that I am a wonderful GM because I try to embrace everyone's creativity but still try to hold down a strong plot line and reasoning for things.

I hope that answered your question! Also, another thing I'd like to say is- if your first, second or third time GM'ing doesnt go as planned- its OKAY! Never give up trying to do it. (:
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