I am also just starting CB and one question that keeps poping up in my mind is that where should i advertise to get best results.
There is no such thing as a best method. If you look around here you will find that different people have achieved outstanding results with different methods. The key is to find one that suits you. Start by having a rough idea of how every method works and then find one that works for you. The goal is always the same: quality traffic.
and how much gravity is considered to be high average low, because some products have an gravity of 200+ and some 50-100 and so and a few products have 400+ also
Majority of the CB products have gravity of less than 100. Anything above 100 means that the product sells, but anything less than that doesn't mean that it isn't a good product. Depending on the method you have chosen you have different range of products to choose from.
For instance if you choose PPC you will have to choose high-paying products to justify the amount you're forking out on advertising. If you choose email marketing you need to choose a niche that provides a range of products to make sure you always have something to sell. If you choose article marketing then you don't have to be too picky.
One important lesson I have learned so far is to
always use your common sense instead of following some 'blueprints' blindly. Why did I choose this product? Who and how strong are my competitors? Who are the potential consumers and how do they think? What are the demographics of my consumers? Do they have enough money to purchase the product? The internet marketing industry is an ever-changing market that is full of dynamics, you need to go with the flow.
The first thing you probably should do now is to read more on different style and methods, after which you could narrow down to one or two methods you prefer and
keep pushing till you see results.
Hope it helps a little. Anyone with more experience please feel free to correct me if there is anything I said that is wrong. Thanks.