There is no way you made $1000/month with 300 visitors per day. Do the math. Did you mean 3000 visitors per day?
Wrong. There are LOTS of ways you can do $1000 per month with 300 uniques. Lets realistically assume that 300 UV equals 450 pageviews. 450 Pageviews = 10% Adsense CTR = 45 Clicks $1(value of one click) x 45(clicks per day) = $45/day $45 x 30(days in a month)= $1350 per month And you can have a greater than 10% CTR. And you also can have a greater value per click than $1. You could very well do not only $1000 with 300UV, but $2000 and even $3000.
Well, 10% CTR seems high...in what industry you are and what kind of visitors you bring in? our visitors must be extremely targeted and you Adsense the same if you have such high CTR...
10% CTR is not difficult. The only niche you would have difficulties having such a CTR would probably be freebies, computer & tech related stuff and make money online. I can't say for sure though, since I'm not in these niches. What you need is a website well optimized for adsense and majority of organic traffic, around 80% at least.
Almost every niche if your business model is text content (no or very few videos or wallpapers or arcade games, etc). You need lots of text content (if you want bigger earnings) and target each article for one specific keyword search phrase. You find this keyword in adwords keyword tool. You would want to target long tail or mid tail keywords. The short ones are to difficult to get in + they are not as profitable as laser targeted long tails. Then you design a high ctr template and implement all the ads so they literally jump into the eyes of your visitors when they visit your website. It takes work, persistance and dedication.