μη particle - nominative
me  may: any but (that), forbear, God forbid, lack, lest, neither, never, no (wise in), none, nor, (can-)not, nothing, that not, un(-taken), without.
πλανασθε verb - present passive imperative - second person
planao  plan-ah'-o: to (properly, cause to) roam (from safety, truth, or virtue) -- go astray, deceive, err, seduce, wander, be out of the way.;
αδελφοι noun - vocative plural masculine
adephos  ad-el-fos':  a brother near or remote -- brother.
μου personal pronoun - first person genitive singular
mou  moo: of me -- I, me, mine (own), my.
αγαπητοι adjective - vocative plural masculine
agapetos  ag-ap-ay-tos': beloved -- (dearly, well) beloved, dear.