Games are weighted based on the day they were played. The value of games on each day are given by a line through the origin and a slope you provide. Games on the last day are equal to the slope while games on any other day are the slope multiplied by the percent of days in the season that have passed.
The weight of the game for the home/away/(or both if it's a neutral site) team is multiplied by the home/away/neutral weighting. If you think performance in home/away/neutral games is more indicative of a teams performance, make this weight larger.