It took me a while to figure it out.. but if you can get ahold of any really stiff packing or smudger brushes, they will make it show up like a pro. The one I used is from the Sonia Kashuk travel set. There's two brushes in the set that've made Bitter work for me really well! Here's two sets they have for her right now..
i use the nyx jumpo pencil in milk. i pack on the color on top of it and it really pops. the pencil is really cheap too. i think i got mine for 3 or 4 dollars at ulta.
youve got some good suggestions. id consider saving up for a good base (like soft ochre) which is something you can use under any shadow to help the color pop. a base is something i think everyone needs that wants a bold shadow.
Use an NYX pencil as a base. They are by one get one half off at ulta this week and I would get milk (white that works under a lot of colors) and horseradish to use under bitter.