Is it too late to save my garden?

[Jennifer]

As you know, it's already mid July. I have cucumbers growing, which are producing. However, they are producing bitter cucumbers and have been affected by some sort of bug that was eating their leaves. I used Seven, and the bug problem has stabilized for now. They are Straight 8 cucumbers though, which I learned today are the second worst producer of bitter cucumbers. But, I can always peel I guess. I also have tomatoes and green onions. The tomato plants were doing great, until the leaves started to curl and turn yellow (although the curling happened several weeks BEFORE the yellowing) so I don't know what's up...whether it was over-watering (which I WAS doing) or tomato leaf curl disease. Either way, they are producing some, but not much. I have removed all yellowed stems and leaves from them cause I hope that might help focus the plant's energy on the healthy parts. *shrug*. Anyway, I started this little garden b/c my apt. complex started a community garden. They fashioned raised beds and brought in soil from who knows where. I'm a beginner in the worse sense, so I didn't fully understand composting or fertilizing soil in order to prepare it for planting. I bought some 10-10-10 fertilizer, a few seed packets, and a few tomato plants and just went for it. My squash up and died, after looking so healthy at first. So, now that I'm researching more and more as I encounter problems, it has just left me feeling like nature is one step ahead...every time I notice a problem, it seems like it's too late. So, I now know that the fertilizer I was using isn't really the best (nor is it adequate alone), the soil drainage isn't quite good enough, and I chose the wrong variety of cucumbers and possibly tomato plants also (I got Beefsteak). I read that I can get a compost ready in as little as 10 days... should I do it, or am I fighting a lost cause at this point? Is there anything else you can suggest I do?