Allways a good thing is to start up and try to recreate Coasters from Rollercoaster-Database (
www.rcdb.com).
Use the Data's to know about importent things, like train-size or which Inversions are used on which Coaster-Type.
Then you can try it out with RCT-3. It's all about practice, because sometimes the path between realistic and unrealistic isn't clear.
You wrote that you wachted Silvarret's vids on Youtube. Thats good, because he's one of the best realistic Coaster-Designers RCT has. But there some others on Youtube, too.
search for Re-Build Coasters, some people that can re-create coasters with the complete scenary can create great realistic layouts, too.
All in all, in the end its practice and alot of play around, after awhile you find your way between realistic layouts and personal style.
BtW, sometimes unrealistic coasters can be great aswell!
Terry Inferno wrotes in a build-it thread that he wants atmosphere, and he is right. You can create a unrealistic layout, but with the right atmosphere in it, it can be grand, and maybe a build-it winner.
Most of the time, the reason why unrealistic build-it entries loose is that the creators are only build a layout with a simple station (most of the time without a station) or build to much scenry that doesn't fit with the coaster.
Maybe it could helpful, that you should think about it, what did you like to see in an amusment park.
If you have some ideas, wrote it up. Good coasters are not be build in 1hour or 1day.
Good Coasters, or better realistic ones are be build with a spend of alot of time in it.
If you want to know, which B&M's Creations here on RCTgo are realistic/unrealistic than it could be hard, because everyone here has an personal different opinion about otherones work.
And no one here can say it 100% corretly which coaster is realstic and which isn't!
(it doesn't matter how good this person can build real coasters himself)
Long text, sry for that. but i hope there is something in it that could be helpful for you
Soo long, Cobra