Jigs are the most versatile lure of all. They can be fished shallow or deep depending on the weight of the jig head. When planning a trip up North, let's say the boundary waters or Canada--you should take a variety of jig heads and plastic bodies to go on them. You can buy jig heads at any good tackle store or bait shop. They come in many colors and unpainted as well.
I, personallly, do not think color is that important. I usually buy black jig heads. Their weights will range from one-sixteenth ounce to one-fourth ounce for casting and up to one-half ounce for vertical jigging. The plastic bodies will range from three to six inches long and I prefer swimming tails, i.e., Mister Twister style. Best colors for me are black, white and chartreuse.
If I was allowed only one lure to fish with, it would be a one-eighth ounce jig with a six inch worm (swimming style) , white for clear water or black for darker or stained water either cast or trolled. All species of fish will bite it.