Good Morning. I use only Taq Platinum for my PCRs and BigDye ™ Terminator v3.1 Cycle Sequencing Kit for my sequencing reactions. I can only talk a few tips about my PCRs. The ideal concentration of DNA is 100 ng / μl. The reagents should all be at room temperature (25 ° C). If I do PCR with the reagents slightly frozen, sometimes the PCR does not work. Magnesium is a powerful catalyst for the reaction. When I have bad PCRs and need to adjust the reaction, I always first change the magnesium (increasing or decreasing) before making any changes in the cycling temperatures. I try to standardize all my PCRs for annealing at 60ºC, regardless of what is ideal for primer. I do this by adjusting the amount of magnesium. I have PCRs that use 0.2uL of 50mM MgCl2 to 2.0uL of MgCl2 50mM in volume reaction of 25uL. I did this so that all of my different primers could work well at 60 ° C. That way if I have different PCRs to do with different primers, I do not need to do in several different cycling. I can do it all at once in a single cycle.