One might benefit from keeping in mind this simple maxim: If the reader is unable to clearly form an impression of the thing that you are describing, try, try again!
Let's see how some writers approached their essays and analyze why they work so well.
"As a lifelong crabber (that is, one who catches crabs, not a chronic complainer), I can tell you that anyone who has patience and a great love for the river is qualified to join the ranks of crabbers.
Take note of these and, as you work through revisions, refine and edit your opening.
If you're struggling with the opening, follow the lead of other writers and skip it for the moment.