You can get into partial mash with minimal new equipment to purchase if you want to jump right in and get started, then you can upgrade later if you want. All you really need is a 3-gallon beverage cooler and a 5-gallon paint strainer bag. My process is basically as follows:
-Get strike water heating in your brewpot.
-Put paint strainer bag in cooler and pour in grains. I do about 6 lbs of grain because I’ve found that my cooler can accommodate this much using 1.25 quarts strike water/lb. It’s the same amount of time and effort whether you mash 2 lbs or 6, so I figure I might as well mash big. Having the cooler close to full will also increase its thermal mass, so it will hold temp better.
-Pour in about half of your strike water and stir well.
-Pour in the rest of the water and stir well again. I also like to lift up the bag and dunk it a couple of times at this point to make sure I get some water in between the bag and the sides of the cooler.
-Take your temp, adjust if needed, and put the lid on. The cooler should hold temp pretty well for an hour.
-I like to take the lid back off and give it another stir when I have about 15-20 minutes left in the mash, but that’s probably not necessary.
-During the mash, heat up your sparge water in your brewpot. I just use 2 gallons for 6 lbs of grain.
-At the end of the mash, lift the bag up and let it drain back into the cooler. Give it a squeeze and get most of the first runnings out of there.
-Leave the first runnings in the cooler and place the bag of grains in the brewpot with the sparge water. Stir the grains in the bag and dunk it a couple of times. Burner can be off during the sparge, as you're really just rinsing the grains and don't need to be continuously applying heat.
-Let grain bag sit in sparge water for 10-15 minutes and pull out and drain/squeeze.
-Add your first runnings and proceed with boil.
I won’t make any claims that my method is better than any other, but it works extremely well for me and requires no equipment you probably don’t already have except the cooler. Also check out DeathBrewer’s excellent partial mash how-to that chicken linked to.
Have fun- you definitely won't regret moving on to partial mash!