Methods are described to create, store, manipulate and characterize positron plasmas. Emphasis is placed on the so-called buffer-gas positron trapping scheme for positron accumulation that uses positron-molecule collisions to accumulate particles efficiently. Manipulation and storage techniques are described that exploit use of the Penning-Malmberg trap, namely a uniform magnetic field with electrostatic confining potentials along the direction of the field. The techniques described here rely heavily on single-component-plasma research, and relevant connections are discussed. The use of rotating electric fields to compress plasmas radially (the so-called “rotating wall” technique) is described; it has proven particularly useful in tailoring positron plasmas for a range of applications. The roles of plasma transport and available cooling mechanisms in determining the maximum achievable plasma density and the minimum achievable plasma temperature are discussed. Open questions for future research are briefly mentioned.