These are the most common 100 Greek words, as presented by the Dickinson Classical Commentaries website. As you review them, try to stay aware of gender, genitive form, etc, and especially principal parts.
There are actually 107 entries, reflecting the different meanings given to prepositions by the case the govern. Particular attention to these different meanings is highly recommended.
ὁ ἡ τό
the definite article
αὐτός αὐτή αὐτό
him- her- itself etc. (for emphasis); the same (with article); (pron.) him, her, it etc. (in oblique cases)
and, also, even
who? what? which? (interrog. pron./adj.)
εἰμί, ἔσομαι (impf. ἦν, infin. εἶναι)
οὗτος αὕτη τοῦτο
ἐν (+ dat.)
in, among (+ dat.)
μέν (by itself)
on the one hand...on the other hand (often untranslated)
ὅς ἥ ὅ
who, which, that
for (explanatory), indeed, in fact (confirming)
οὐ, οὐκ, οὐχ
not (with indicative verbs)
λέγω, ἐρῶ, εἶπον, εἴρηκα, λέλεγμαι, ἐλέχθην and ἐρρήθην
say, speak (of), recount; pick up, collect, count
ὡς (introducing purpose clause) (+subj./opt.)
ὡς (introducing indir. statement)
(introducing purpose clause) so that (+subj./opt.)
(introducing indir. statement) that
εἰς (+ acc.)
into, to, towards (+ acc.)
ἐπί + gen.
ἐπί + dat.
ἐπί + acc.
on to, against
κατά (+ gen., acc.)
1. κατὰ γῆν 2. κατὰ φύσιν 3. κατ’ ἔθνη 4. καθἕνα
down (from or along); throughout, according to (+ gen.; + acc.)
1. by land 2. in accordance with nature 3. by nations 4. one by one
ἐγώ ἐμοῦ, (pl.) ἡμεῖς, ἡμῶν
πρός + gen.
from the side of, in the presence of (+gen.)
near, at, in addition to (+dat.)
to, towards, in relation to (+acc.)
πρός + dat.
near, at, in addition to
πρός + acc.
to, towards, in relation to
γίγνομαι, γενήσομαι, (2 aor.) ἐγενόμην, γέγονα, γεγένημαι, ἐγενήθην
become; be born; happen, be
if (+ subj.)
διά (+ gen., acc.)
through, during, because of (+ gen., acc.)
πᾶς πᾶσα πᾶν
every, all; whole (with article)