I put the resin on the balsa and scrap it off with a card, then lay the glass down on the damp balsa. That way you're sure to get minimum (light) resin and glass doesn't get dragged around. You really only need enough resin to bond the glass to the surface and 1/2 fill the weave. I use unthickened resin so it penetrates the wood. When dry, sand, and apply a second coat of resin, with some filler if you want but not necessary, to fill the top 1/2 of the glass weave. Scrap again to remove all excess resin. Sand again. Then use quality automotive filler/primers to achieve level of smoothness you want.