Broad question, but ill try to help.
Have an idea for your character and stick with it.
Certain skill overlap in what they can do, don't invest in two skills that do similar things (I.E. medicine and survival both heal in different ways, energy weapons and guns both kill stuff.)
Plan your character. Certain perks and have S.P.E.C.I.A.L. requirements. Make sure your S.P.E.C.I.A.L. can get you the perks you want.
That's all pretty general, have fun