Best is to do it offline in thos small tree farms with a skill boost car. No traffic and constant drift, sideswipe skills just add some skill song to it and you are set to make heaps of xp
I was once at 1 . 3 mill just drifting up and down the airstrip must have went up and down at least 150 times and as I was about to stop to collect the points I hit the Lampost at the bottom of the strip - the day I almost felt like crying
Waste of time as you don't get anythink if it's over 300,000 as you only get 3 skill points at a time regardless if you have 300,000 or 300,000,000 skill chain