First of all, you need to have some good base pattern papers. I only buy my pattern papers in the sale - they're cheaper, and they're still just as pretty even if they're last seasons designs! You can only use so many at once, and some of mine have stayed in my pack for ages because I feel they're too beautiful and need an extra good cause.
I personally have to keep mine in colour order, mainly because I have slight OCD. But I don't think it is a bad thing - if you think, ooh I need a blue to go with this, you can put it next to that section of your papers and see which ones look good, rather than having to sort through them all.
I also have a lovely box that my grandma bought me for Christmas to keep them all ordered in - because I get very particular with my lovely pages!
Next, you'll need a good set of base colours. These can just go alongside the pattern papers, but if you fancy a half and half design then you'll have colours to match! You can always cut them up for layering as well if you don't like half and half pages.
I also collect any scrap paper that I think will come of use at any time - I won't have a particular idea for it, but I know it will come in handy at some point! I have just ordered my mums scrap paper into her new sorting-shelves (In colour order of course), as my selection isn't as developed and because I don't have a full room I can dedicate to craft!
Next, you'll need things to make the pages more pretty, my favourite kinds of things are; brads, buttons, beads, wire, glitter, flowers, punches, cut out designs, lace and fabric etc. To organise mine, I have a very handy compartment-ed box.
Then, there's just the standard crafting tools such as; scissors, double sided sticky tape, pritt stick, hot glue gun, ruler, rubber, pencil/pen etc.
I also believe that you will need a guillotine, I've tried using scissors but it just doesn't get the same results.
Now you're ready to start!