Using thinning scissors with the lie of the hair - never against it - trim the neck so that the short hair blends smoothly with the longer hair. Carefully monitor how much you are taking off - err on the side of too little, rather than too much.

By using a Mars Coat King (size 20) the dead hair is easily caught up in the stripping comb.  This tool is great for puppies changing coat.

You may wish to use a Mars/Mikki stripper to remove stray hairs or undercoat along the topline to obtain a smooth finish. Hold the skin taught and then drag the tool gently over the dogs back as if combing the back, taking care not to scratch or nip the skin.  This tool must be held upright so as to only remove dead coat.  If used on an angle they will cut healthy coat.  Do not be heavy handed with either of these tools otherwise your
dog will look over trimmed and you will lose that natural look you want to achieve.

Another tool that can be used to remove dead coat is a grooming sponge.  Firmly slide it in the direction of the coat and you will remove dead coat without cutting healthy shiny coat.

Whilst the Coat King and the Strippers take the bulk of the excess/dead coat away, nothing finishes off better than hand plucking. 
There is an art to this and it takes practice.  I find it easier to use a latex glove to help grip the coat. 
Only do in short sessions otherwise the dog will not be comfortable with it.

If you feel you are not able to hand pluck then the use of a grooming sponge will do a similar job. 
This is a timely part of the grooming process but the end result is worth it.