Roblox Game Guide, Tips, Hacks...

I use CmdUtl by Anaminus. It's a great plugin and most of us in EBR are using it (if not, all of us). As for tips, just have patience and make it fun for yourself. Get a bowl of snacks and build something you love. Patience is definitely required because the professional builders are spending around a couple months or even more to build their game. It's something you need to spend a lot of time in.

If you need help learning how to use studio, I suggest just playing around with each button and tool inside of it and seeing what it does. Ask around to see what something does that you don't understand.

There really is no "secret" to "pro builds". It's just how much patience the creator had. They're the one that spent a ton of time on the tiny details.