Investors like to build relationships over-time... you hook them in with something interesting you're doing and then gradually keep sharing your progress and achievements even before "officially" fundraising.

AngelList is a great source (for Europe and the US) in getting to know which are the key investors with expertise in your sector and actually make investments (which is key). Find the companies they are investing in and contact the founders of those businesses asking if they have a good experience with them and might be interested in making an introduction for you.

A lot of early-stage and angel investors get good deal-flow and often now limit their correspondence fro warm introductions from people they know - so you need to start with that. Following and interacting with the investors via Twitter, Quora, and their blogs - with insightful points - will also earn you a few brownie points.

For Europe, this is the best crowd-sourced list of investors there is: https://docs.google.com/spreadsheets/d/10S7_jBpRoWuNMnOYpkjFJArt76dPhFw0tIR7E_ndgnk/edit#gid=0

If it was me right now... I'd research 5 of the best angel investors I could that seem to be active and focussed on the type of business I was in, then reach out them via email and/or twitter. A very brief email noting why I was contacting them (they've invested in similar businesses) and a few quick lines what my venture is - with a one page summary PDF attached (nothing else). I'd also assess my network to see if anyone knew them directly and could put in a good word for me.

Hope this helps a little bit in getting started,