Everybody here has given a lot of helpful techniques about how to start pencil sketching.I totally agree with all the answers. But I would like to add few points in a total different prospect i.e. the Psychological side of it. In my opinion there is nothing easier than sketching. I am telling you from my personal experience. Two years from now I knew nothing about pencil sketching, but now I can convince myself that I have achieved a great deal of improvement in sketching.I never perused any formal education on art/ sketching. I am a self taught non professional artist. few points that i would like to recommend you to start with
here I take the freedom of assuming you as a beginner, so before getting into the action you should watch some related videos or read some blogs.that helps a lot. there are few things that you should have.
1. strong inspiration: every artist has their own inspiration. its what makes you believe that you can also be a good artist.
2. motivation: without motivation you can't exploit your potential to the fullest.
3.dedication: you should literally forget about sleep, hunger , time etc. while you are working on your art.
now focusing to your question, following are some points you should start with,
1. observe: this is the most important part. try to segregate the whole reference image in a range of different shades. analyse the light effect and intensity of shadows.
2. reference selection: this is the toughest part for me. chose only those images/ or subjects that really really like.otherwise you won't be able to give your complete dedication to draw it at the first place. you will start losing interest midways.
3.time: give excessive time. remember "no masterpiece can be made overnight".
4. never be satisfied: never be fulfilled by your work. perfection is an eternal process. there will be always scope of improvement.
