Answers from my personal experience on 6mm infantry:
- I place some double side tape on ice cream wood stick. I remove minis from sprue (when on sprue) and after cleaning flash/mold lines, and place them on the stick:

I undercoat and then I paint them:

Once painted, I glue them on bases (bases have been spray undercoat back before):

As each mini base is to high, I place some wall gap filler on the base with a sculpting tool and a wet brush (wet brush to gently remove gap filler from minis feets):

Then I mix fine sand, wood glue, water and color to add texture to the bases and I apply with a brush (use a wet brush to remove mix from minis). Once dried, I dry brushed the bases:

You can place a few drop of Devlan Mud, Gryphon Sepia or Babad Black GW washes here and there to add more colors on the bases.
For my necrons, I used a different way. I bought some Woodland Scenics fine and medium colored ballast (Thanks to Onyx to share this tip). I mixed some fine one with medium and after applying some wood glue on the bases, I directly added the ballast mix:

Tufts are made by Mininatur/Silflor (short tufts range is great for Epic). They are sold ready to be used, just pick them and glue them on the stands. Different colors are available:

Quite expensive but very very easy to use.
For green flock, after long time search, I finally found the brand GW was using in the past old day to base their epic minis, it's some
Javis Premier Range Turf Mid Green or Light Green:

It's some very nice basing material. Just add here and there some small tufts and you'll have a nice base
