all's fair

When you first start running games, you fear doing things wrong. That fear can be crippling and often leads to other negative thoughts. Some of these can warp into self deprecation making you think you’re not good enough, funny enough, creative enough, etc. Let me be clear here. You are enough! 

The more I watch other GMs talk about what to do (or not), I realize that it is simply an opinion. There are no real hard rules on running a game, just suggestions. One in particular I would strongly recommend following like staying consistent with rulings, but others depend entirely upon your gaming group. No one is here to give you scores, this is no competition, and you’re not going to get fired (trust me, your players are happy that you have taken on this role).

Probably the number one advice I could give first time GMs is to have fun. This is ultimately a game. Meet in a tavern, fight the bandits, save the princess, be rewarded by the king. You do not have to come up with everything on your own. Then, listen to your players as they suggest different ideas and stash it away for the future (or add them on the fly if you are comfortable with it). The more you run games, the bigger your GM chest of story plots, monsters, NPCs, etc. will grow, and with it…more confidence to continue the journey.