For the couple months I used my eGo I used the LR Mega eGo atty with a Blue Foam coil in the Cartridge.
I cut a strip roughly 14mm x 55mm, and coiled it loosely until it was slightly larger than the opening of the cart. I put in about 40 drops of
juice, then the coil, then about 3 more drops on top. You might be able to fit more but at the time that size coil and amount in cart seemed to be perfect for me. Lasted 3-5h depending on how often I vaped and did not leak. I was using a 80/20 PG/VG mix so best bet would be to try different sizes and see what works best for you.