It's really important to be in a comfortable place for your first time. Don't be in a spot where you could be caught (parent's house) because it's easy for paranoia and worry to set in. Wear comfy clothes and don't invite anyone who you find slightly annoying because they will really get on your nerves after you are tripping...guaranteed!
Shrooms can be really fun. I've had some wonderful times on shrooms. If you have an intense trip, they can carry a heavy body load and the visuals can be amazing.
But never treat mushrooms with anything but respect. I have seen people wig out on them and it's not pretty. Please, please do not take more than 1.75g (or 1/16 of an ounce) for your first time. Wait two hours and if you're not where you want to be then you can take more. If you take an entire 1/8 your first time out, it can be too overwhelming.
IMO, shrooms are very different from MDMA. As far as physical effects, there's no jaw clenching like on MDMA. My stomach always feels a little uneasy on shrooms. I don't know if this is common but my eyes water a lot and I feel the need to pee frequently.
Shrooms are psychologically different from MDMA too. Shrooms are much more introspective. During one trip, I found myself feeling the entire emotional (anger, sadness, happiness) over and over again. During another trip to a modern art museum, I stared at a beautiful Georgia O'Keefe painting for 15 minutes. Time moves slowly on shrooms while it speeds up on E. I've found that music really has a dramatic effect on your trip. The happier the music, the more uplifting the trip.
I hope this has helped you. Please don't take too much your first time out and enjoy! Mushrooms are amazing and I have a healthy respect for them.