This has been discussed many times before and rather than repeating a lot of those things here, I will direct you to one of the best resources on this topic.
Clarity CEO Dan Martel recently released a video "Raising Capital Like a Pro" that covers most things you need to know about fund raising. Here is the link: http://youtu.be/7dew9hhWBB4
First of all, it's crucial that you know exactly who you are looking for. Without that knowledge, it's going to be hard to find that right investor.
How is investing in your competition? Who would be your dream investor? What are the values your ideal investor has to represent? How much capital do you want to raise?
Once you have questions like that figured out, it's much easier to determine where the right investors hang out.
LinkedIn is one of the best places to connect with investors from my experience. LinkedIn groups are a great place to start making connections.
When it comes to "who is right and who is not?", the quick answer is "Listen to your gut".
First and foremost you need to interview investors as much as they nit pick your team. Right fit is a great way to put it. You want strategic investors whereby they can introduce you to his/her network. AngelList is great as well as many other fundraising sites, however... one thing rings true with ALL of fundraising opportunities. People are not looking for a good idea. They are looking for the team, market size, traction, then idea. Good luck!