How can I make my small garden plot better for producing good veggies?

During the growing season you also need to add vegetable fertilizers

Do you have enough sun? That can be a big factor.

Get a 5 gallon bucket with a lid. Pu it in a place where small will not bother you. Over the winter dump all your raw vegetable scraps in the can - shavings from carrots, wilted lettuce, potatoes peelings etc. No meat, nothing cooked. By March or so, you will have a liquid mash. Mix this very well into your garden 30 days or so prior to planting. Will bring tons of worms. It will kill any plants there as it is very strong. But after 30 days it will calm down. Very STINKY. But it will produce! AND it is free.

I have found that self pollinating squash plants has made a tremendous difference in their production. This is accomplished by taking a flower from higher up the plant and brushing it against the flowers lower on the plants. Additionally, we had a much better yield for the entire garden with compost and a reasonable amount of all purpose fertilizer added in at the appropriate time.