Be an adult.
That is all.
Or, to expand on that…
It took me a few years to work that out. So long as it is not done at the expense of another’s feelings or dignity, there is no wrong way to be a Lego fan: you can be a MOC maker, set displayer, build the set and sell to pass on the joy, minifig collector, city designer, mosaic designer, young or old it in between, Large scale, small scale, microscale, scale modeller, abstract builder, space, city, castle, Pirates, licensed themes, vintage sets, modern sets, gear collector, game player, legographer, custom user, gluer or cutter, challenge setter, machine maker/engineer, visual artist, theme follower, or just get whatever you feel like.
You do not need to be a social person. You can be a Lego fan on your own, or with friends, or with complete strangers.
If you don’t build, you can be a supporter of the builder in your family, help out at user groups/conventions/displays, read blogs (thanks!), run an event, coordinate a group build or just like to look at other peoples models.
You are still a Lego fan, and don’t let anyone else tell you otherwise.
Support each other in your love of Lego, even if you love it differently (this can of course apply to any fandom you identify with)
So… to recap:
Be an adult
Don’t put others down for loving it differently.