And i'd tell my younger self to NEVER EVER part with them. EVER. Because Nostalgia is 9/10ths of the Law
I kept all my childhood toys. All but 3 of my childhood TFs are in my collection today (the 3 missing were stolen; I never wilfully parted with them).
But if I were able to go back in time and give myself one piece of advice: keep my toys away from sunlight.