Reapplying thermal paste to my MacBook Pro?

I was wondering how I would go about doing this for my particular model? Some people are saying that I should never spread the thermal paste after I put a drop onto the parts and that instead I should just put a drop of the thermal paste and just put the heat sink on top, leaving it alone. I haven't been able to find a 100% definite answer about this, so is this a good idea for my particular model? Should I do the "vertical line" method for my i7 processor without spreading it? I feel like not spreading it would only protect part of the processor with the thermal paste.