Until you can afford a harness, use wrist-straps.
You basically tighten the straps around the bar at grip-width and then grab the loose ends with your hands in a neutral position above the bar... The closer you can get your hands to the bar the better.
I'm personally much more stable with that setup vs. a cross-grip.
One thing: The bigger you get (shoulders and upper-chest wise), the more "comfortable" front squats become.
As a skinny beginner I hated the exercise, now I don't have to do much more than raise my arms and the bar fits perfectly (though I go low in reps on those and thus still use the straps for safety)...