One good rule of thumb is that you must attain 75% of take of speed by 50% of the TO run. If not abort, unless you really really know what you are doing!
Also, better to hold down in ground effect to build speed than to climb out with low airspeed.
And most of all, if all goes tits up, fly a controlled crash landing (if there is such a thing), and don't just stall into crash with nothing but the hope of a lucky outcome!!
SS