When fishing a jig and minnow for walleye there are a few things I like to consider when selecting the correct jig.  The first thing is picking the correct weight.  Generally, you like a jig that is as light as possible yet still make contact with the bottom.  The second is color, this is a bit more of trial and error but I prefer more subtle colors in clear water and brighter colors in dirtier water.  The last thing I like to consider is hook gap.  I feel this is the most important of the three.  Your hook gap needs to match your minnow size.  As you can see in the picture below, if you use a larger minnow like a shiner you need to use a jig with a wider hook gap.  If the hook gap is too small you will miss a lot of bites.  If you plan to use a smaller minnow like a fathead then a standard jig will be just fine.  Now that you’ve picked the right jig get it out there!  Move it slow and keep it low is my rule of thumb.  Good Luck!