Σεαυτὸν αἰδοῦ.
Have respect for yourself.
The form αἰδοῦ is a middle imperative from the verb αἰδέομαι. It can mean "feel shame," but especially when it takes a direct object, as here, it has the sense of "feel fear, awe," and thus to venerate or respect. The noun αἰδώς also covers that same range of meaning, from shame and fear to awe and respect.
Ἀεργοῖς αἲὲν ἑορτά.
For lazy (people), (it's) always a holiday.
The saying is reported in one of the idylls of Theocritus; you can find out more at Wikipedia: Idyll 15. The adjective ἀεργός is an alpha-privative: ἀ-εργός, not-working, and it is being used substantively here: lazy people.
Ζητεῖτε καὶ εὑρήσετε.
Seek, and you will find.
The words are from the Sermon on the Mount in the Gospel of Matthew; find out more at Wikipedia: Matthew 7:7-8.
Οὐ νυκτὶ πλεῖς.
You are not sailing at night.
This refers to the fact that it is the night which gives you a way to steer your ship, using the stars. To be sailing by day, not by night, means to be doing something in a haphazard way without a sense of direction. As Erasmus notes, however, the saying also appears in the proverb collections without the negative — νυκτὶ πλεῖς, "you're sailing by night" — with the same negative meaning, as sailing in the dark can be dangerous too because of rocks and shoals of coastlines. Traveling by sea is dangerous at any time! (The Greek were not very adventurous navigators.)
Δεύτερος πλοῦς.
The second (way of) sailing.
This referred to sailing by the power of rowing, rather than with the wind. Obviously, it's more work — but you still get there, so the saying refers to a next-best route to success, one that might take more effort on your part. You can see the Greek root of δεύτερος in Deuteronomy, the "second book of the law" in the Hebrew Bible; see Wikipedia: Deuteronomy.
And to finish up, here's a random proverb and a random LOLCat too:
