In general, multiplayer action gives more points than single action, but it takes longer and you risk quitting.
IMHO, the best for maximum XPs is
1) play at least one hole per day to get the continuous day bonus of 880 XPs,
(one hole from the course display in the "community" tab)
2) play single tournaments, 190 XPs per 9 holes, 400 XPs per 18 holes plus the strokes taken, in the shortest time.
Thus, 1100 or 1300 XPs are possible for the first tournament of the day.
Some have combined this with buying XP boost (e.g. 2x CDP bonus in one hour's boost) but it seems like "no fun!" for me.
Most disappointing thing for me is CTTH games, 5+9 XPs :(