I am currently studying C# and I really want to get a good coding style from the beginning, so I would like to hear opinions from you professionals on this matter.
Shoul
As you said you are studying C#
So my vote will be this style for you
bool parseSuccess = double.TryParse(stringToParse, out dblValue);
if (parseSuccess) ...
If you are studying you will have lot to learn and the above style clearly tells you that TryParse return a bool, so you won't have to worry or find whats the return type for TryParse