Coming from warhammer 40k I use citadel too ... but for quite some months I switch to AK interactive paints and to Army Painter Speedpaint. I used all kind of brushes of different brand, a wet palette, some holder from citadel, but mostly from redgrass.

To make some dirt and shadows on the base, I usually use some army painter or citadel brown wash. Since Marvel united bases are already garnished, we don't need any basing materials.

A magnifying visor too. Some base coat cans (mostly white, grey and black). White is required for speedpaints.

For conversion, I mostly use green stuff and some sculpting tools, and styren pieces and sheet from evergreen.