Well you could do it like I did CFII first with the FSDO then the MEI with a DE then the CFI-A in a non complex plane like my warrior. Now if you are set on the CFI first then I would fallow up with the CFII. Most schools and instructor jobs require you to have CFI/CFII and could care less about the MEI. You can start to get an immediate return on your investment with the CFII it would take a while to get any return from a MEI.