When making neutral spirit it is very important to filter the spirit through carbon as it removes a substantial amount of bad tasting contaminants. Personally I recommend using a fuselex carbon filter because they are made from stainless whereas a lot of other filters are made from plastic. Some plastics are soluble in alcohol, not something you want to be drinking!
To filter the spirit cut it down to 40% with water (use this calculator) and filter as slowly as possible through the carbon. You can filter 10-20L of 40% spirit through 300g of carbon.
If you do not want to buy a carbon filter you can age the neutral spirit on carbon for 2-3 weeks. Use 10g carbon per litre of spirit and shake the container occasionally.