Grab a bunch of fc mates or ls mates and add a certain item on ur wishlist, wait for the demand to imcrease till becomes an orange star and wait for crafters to flood that item's list.
After there is a lot in stock, un wish list it and wait for prices to drop as ppl will be like wtf, y aren't they selling.
Buy them cheap and win lol.
Always make sure to undercut ppl and be at the top as ppl will usually but the 1st few on the list.
Always check the MB every couple of hours to see if the items u kept an eye on are still hot or not.
As a non crafter, i have been capable of making a million gil since 2.2 release but i kept all the vanity and tidal barding for myself as i wanted them lol!
The MB crashing is inevitable, milk it while u can as each time when a wave of new stuff is added to crafting; the MB will thrive once more only to die again.
When that time comes again, stock up on whatever u think will become valuable and sell it once the next semi big/ huge patch hits.