I want to be a good full back for my rugby union team I have only been playing for a while any tips and tricks to be a good fullback btw I play under 13's

To be a good fullback you should practice catching (kicks), tackling, kicking and work on your attacking game. Go to youtube and watch Mils Muliaina, Leifgh Halfpenny, Rob Kearney, Isreal Dagg, Kurtley Beale, Isaia Toeava and Ben Foden. For tackling watch Halfpenny in particular,Hope this helps!