They get an item of their level +1, an equal level item, and an item of their level - 1, and they also get some gold, valuing at a magic item of their level -1.
Also, according to the rules in the dmg, they also get all the mundane equipment they want for free.
However, and we are now entering house rule territory, for characters of levels 2-4 i'd give less magic items and maybe less gold. Something like this:
2nd level-> one second level item plus 100 gold plus mundane equipment
3rd level-> one third level item plus 520 gold (equal to the value of a second level item) plus mundane equipment
4th level-> one third and one fifth level item plus 680 gold plus mundane equipment