Tracing your ancestors can be tricky. Here are some useful starting points.

When you first begin research into your family tree, don't under estimate how many pieces of paper you are going to accumulate.  Try to set up a filing system that helps you keep your documents together and in a logical order. Collect all the paper work and family photographs you have. Try to find birth, marriage, death certificates. Talk to your relatives and record as many of their recollections as possible but never confuse family stories with facts, check everything. When collecting family stories you may find that one person’s recollection differs from another.  Dates can get mixed up, locations and names are transposed.  More often than not these stories are very useful as supporting evidence that you're on the trail of the right person. Try going back to an interviewee, both with new finding and a transcript of what they said.  They may be able to add something more. Draw a rough tree from the start.  Many families use the same names across generations, this can get very confusing and a tree showing each generation can help.    
Family photographs can give clues.  This photograph of the Owen family was taken in c.1915 and two of family were home on leave from the army. Jack Cooper had been discharged as a result of being gassed, and wore a badge to signify this.