When reading a book I have them look for it. Keeping one on a card for reference. Making a game out of it. My son does well with verbal rewards and high fives.

Make a game, my mom used candy, or stickers as a prize, how many she gets right is how many she gets, and keep working on the ones she doesn't until she gets them. Also put them on the things they are like door put it on a paper and tape it to a door, so she sees the thing and the word being able to associate the word and the thing together. Keep working and dont give up you're doing great! If I think of anything else I'll comment!!

Make a lil song