Akademik

Не зная броду, не суйся в воду

Never start doing anything if you have not carefully considered possible difficulties and dangers

Var.: Не спросясь броду, не суйся в воду

Cf: Before you go into a canyon, know how you'll get out (Am.). Do not wade in unknown waters (Am.). If you cannot see the bottom, do not cross the river (Br.). /It's/ no safe wading in unknown water (Br.). Look before you leap (Am., Br.). Try the ice before you venture upon it (Am.)

Русско-английский словарь пословиц и поговорок. Академик.ру. 2013.