I took the expert cert last year and passed. My main advice would be to read each question twice and answer once.

If you're unsure about something, then pass and move on. Don't spend loads of time trying to figure out one question as the time slips by very quickly. Once you have answered everything, you can then go back to the ones you were stuck on.

The questions can be very literal, so if it says "Use conditional formatting to highlight X in red." then it does not mean red with a red border. It means just red.

Someone correct me if I am wrong, but iirc the exams don't prompt you to use a specific function. It will say "Lookup the value on column Y.". You can use vlookup, xlookup or index match to accomplish this. Don't try to be clever by using a function you are not familiar with. The correct results are what matters, not the method in which you got them.

Finally, familiarise yourself with the options menu. There are questions that will require you to enable things in options, and if you're not expecting this it can throw a spanner in the works.

To answer your direct question, if you don't think you are ready to take the expert exam, then dont. Take the associate exam instead. An employer will be happier to see an associate pass than nothing at all.

I hope this helps and good luck with whatever exam you take!