With accent marks:
Гото́вь са́ни ле́том, а теле́гу зимо́й.
Get your sleigh ready in summer and your (horse-drawn) cart in winter.
This proverb reminds us to plan what we want to do and what we will need to do in advance so that any difficulties and unforeseen situations do not catch us by surprise.
There is almost the same proverb in English: "Repair your cart in December, in July your sledge remember".
Other Russian proverbs
Start taking care of the dress while it's new, and of your honor while you are young.
Crowded, but not aggrieved.
Hurry to much and you will make people laugh.
~ Seven babysitters make the kid to lose an eye.
Water wears away a stone.
You are greeted by your clothes but bid farewell by your mind.
Do not dig a hole for another one, you will fall into it yourself.
Water does not flow under a lying stone.