If it isn’t possible to buy organic, you can use theDirty Dozen / Clean Fifteen guide to see which produce should be avoided (Dirty Dozen) and which produce is acceptable, even if not organic (Clean Fifteen).
If organic produce is not available at your local grocery store and you have to buy regular produce, make sure you wash your produce in a solution of 1 TBSP apple cider vinegar and 1 cup of water. Soak for 5 minutes, stirring occasionally, then rinse well.