Tempy, I am with float on this one. Have a look at this clip...

Tempy, I am with float on this one. Have a look at this clip from Nick Radge about an overall philosophy of trading and see if it strikes a cord for you.

http://donktrade.com/reading

Good luck with your trading, and as Float said, there are other things to look harder at than the Market Depth. Try to determine a 'style' of trading that suits you, and then from there start to work out what tools are going to be useful to you.