Thought I should start a thread that had some general tips on for those who have just started and joined SOD.
First tip for the list - Train, train, train.
Make sure you train as much and as often as possible. Training continues while you're doing pretty much anything except when you're assisting with rooms in safehouses.
With training, the shorter the amount of time you train, the more points you gain, so if you're going to be on for an hour or so, train for the lowest amount of time (5 minutes) repeatedly so you can maximise the benefit. Before signing off, start training for the maximum amount of time that you can so you can continue building your levels while away.
Also look for some of the locations that will increase your max level of training on each of the disciplines.
i.e. at the College Campus Gym (37,21) you can increase your max strength and close combat skills to 74.