I think you have started by reading posts on this site! Visit as many other sites as you can find.
Create a file to keep all the gems that you will inevitably pick up. Keep the data in group (e.g. a sub-file for engine, electrical, carburation etc.) so that you stand a chance of finding it later.
Have a Word document to keep web addresses but remember to add a brief description of what was on the site that interested you.
You will see many machines or elements of the machine that take your fancy. Copy the picture into a photo's file for future reference.
Whilst you may create something that has never been done before, more likely it will be an amalgam of things that other folk have done. Use their knowledge (with perhaps your own slant on it) rather than re-inventing the wheel.
If you don't know - ask. The only stupid question is the one you don't pose (although sometimes some do invite 'off message' responses!).
You will start to develop an idea of what it is you want to create, whether it be a pristine original machine or the wackiest bobber known to man.
For your first build I'd suggest that you keep it simple. You WILL make mistake or go down blind alleys as you learn.
Be realistic on what you want to achieve. Access to a lathe, mill and welding equipment means you can extend the envelope of what is possible to do yourself. You can, of course, pay people to do these things for you but that will quickly eat up a lot of dosh.
Take pictures. Sometime they are necessary to get the Foo Foo valve back together or just remind you of your starting point and let you see you
are making progress.
When stripping components try to keep the sub assemblies together and where possible the associated fasteners. A selection of self sealing bags is good for this as are large plastic bins.
Set yourself objective to complete a task but still take your time. In my experience, most jobs take me far longer than anticipated. Don't knock yourself out with work - what you are creating should be fun and not a chore.
Try to work on one element at a time rater than have a dozen in various stages of progress.
If you a crating, say a street tracker or bobber, do a trial build first. It's a bit of a bug*er to find that you need to weld a bracket onto your freshly nickel plated frame.
When you have everything as you want it strip it down and do the final build. Replace old tired fasteners with new zinc plated or stainless items.
If you can't afford a professional paint job it is possible to get a perfectly acceptable finish using spray cans.
Even if you are using a pro to do the paint, do the initial surface preparation yourself. This save a few pennies although not many in my experience.
You can take the extra time needed fill, rub down, then keep re-filling and rubbing where necessary until you get the surface perfect.
It is worth the effort when you are rewarded with a mirror like finish.
There is a vast amount of information out there for you to tap into. There are also a lot of knowledgeable individuals that are happy to take the time to offer advice and help.
Use it and your first build can be a stunner!