How to make Visual Studio not put { on a new line?

Go to Tools -> Options -> Text Editor -> C# -> Code Style -> Formatting-> New Lines

Here there are a lot of options. Remove the check on all options here to never put the open bracket on a new line.

EDIT

The section New Line Options for expressions does not relate to placement of code in conjunction with brackets, so those you don't need to touch.

You can change that in the options of your Visual Studio. Go to Tools -> Options -> Text Editor -> C# -> formatting -> new lines (or something similar, I only have the german version of visual studio). You can then change where you want to put the brackets into the next line and where you don't. Personally, I removed all the options, but if you want to have a new line e.g. in loops, there are many options to customize this.

Bear in mind that if you're using Resharper the above procedure won't help, since Resharper overrides the native VS behavior. If that's your case go to Resharper > Options, Code Editing > C# > Formatting Style > Braces Layout, set all top "Braces Layout" options to "At end of line (K&R style)".

Took me a while to figure this out, so I hope it helps someone.

For all the Mac Users out there, this is how I solved it:

Preferences -> Source Code -> Code Formatting -> C# source code -> C# Format -> Edit

There you can change it under the Category: New Lines