If you need to instruct to build time and experience; I would suggest going the traditional route, getting your CFI ratings in the following order: SE CFI, CFII then MEI. Some of the reasons being; Not many folks get VFR Multi ratings these days. Not many Multi students, period or relative to SE students. Years ago VFR Multi's were popular, though haven't been for many years. Most of the Multi instruction you will give will involve a significant degree of instrument work. As a new instructor you will not likely be seasoned, proficient, safe and comfortable enough to be giving instrument instruction in a twin. There are always exceptions though I recommend polishing your instructional skills with the SE aircraft first... Good instrument and Instrument instruction skills will make life much easier when it comes time for the twin. Personally, I got my MEI first but already had a bunch of time and did not need to instruct...