There is a lot of advice out there but, the rough outline, stretch frequently(what that entails is determined by how flexible you are today), before making any attempt, warm up, stay hydrated, have an empty stomach, and preferrably try after a hot shower. You can't force it, it should be like settling into a position not dragging yourself into position. The leaning forward position(called X-position) works for some people but, it never struck me as a beginner method. Laying on the floor and kicking your legs over your head (depending on flexibility you can "walk your feet down a wall" or just put your toes on the floor. In the back position you should be able to progress until your knees touch the floor, the goal then is to progress until your knees are on either side of your head then shoulders... Its good to constantly be aware of where you feel strain(if its your spine you have reached your limit for the day). when you start getting close to reaching, I recommend getting into position and remaining stil just hold it, then slowly (take your time) try to relax, you don't want to be tense, relax and shift your knees forward and exhale and take progressively shallowrr breaths to gain ground... eventually you will touch your forehead or nose and you will realize you are ready to go for it.

If you are currently six inches away from success, I dont expect to get there within a month or even two... pace yourself do regular stretching (V-sit, stuff like that) daily, and position stretching a couple times a week (half an hour of trying to get there or at least into position) seems like a big investment of time but, the first time I made contact was by accident.