Agarose Gel Electrophoresis - Troubleshoot (Jan/18/2007 )

sometimes rough pouring of sample in the gel cause wavy bands (i am sorry if i am wrong)

Aren't "smiley" gels caused by too much heat? Running at a higher voltage produces more heat and this can make the gel warp. That's my understanding anyway.
I run my gels at 100v for 20-40 minutes. These are 1% in TAE. And if I don't need all the lanes, I usually skip the first one.

How much you reuse the buffer, high voltage and agarose high concentration could make the gel look because for eg if you have a high conc (smaller pores) and use a high V you are pushing the DNA at high speed in a very narrow place. to much reuse buffer will distord the bands because the salts conc aren't at optimum. Also high vol could cause high temp and this have 2 effects: smily (cause by uneven heat) 2nd if to high temp could degrate the DNA. Hope this help.