Thanks for all the great advice. A major problem I have is that I just don't feel I have enough knowledge.
Best thing to do, and I think something that should be ingrained in all writers psyche it to ask questions, loads of them.*
When I start a project it's a bit like death by a thousand questions for me - I will go through my ideas and take them apart, tiny piece by tiny piece. Take your ideas and ask every possible question and flesh it all out. If you get to an answer that you say 'I don't know' research it or come up with answer if it's an issue that your creativity can only solve...but
don't allow it to be left as unknown.** It can be about your settings, your characters, whatever. Ask why is your main character doing what he/she is doing, ask what he/she is wearing, hell if it's relevant ask what do people in your world eat for breakfast.
As for historical stuff, there's plenty of free stuff on the web to get you started plus a wealth of other info that you'll find useful to help give you further ideas for your non-historical ideas.
* It's one of those things that writer's courses recommend and I do think it's a good thing - observe and question when you're about day to day. See someone on a bus? Ask yourself why do you think they are there, where are they going - invent a fiction for them! (all in your head of course
)
** You can take this process far too far, so it'll be up to you to decide when you've done enough. When you have experienced it for a 'full cycle' so to speak, you'll probably get the confidence to stop researching and start writing in earnest.