First, what is a good sturdy type of drill bit to buy? It seems like I destroy a lot of bits doing all kinds of metal/wood drilling. They usually start drilling fine but soon dull and overheat. I have tried using oil but that doesn't seem to help the drilling much or preserve the bit. Maybe I should have a specific cutting oil???

Second, is there a good bit sharpener available? I've tried a couple over the years but either I get the angles wrong, the sides assemtrical or perhaps I've overheated the bit so much drilling that the temper is shot.