5 or 6 traits would be enough.
Traits:
darkvision 60ft
extra skill proficiency, 3 max
skill proficiency+expertise, worth 2 trait "slots", 1 max
2 tools or languages or weapons, 3 max
+1 armor level of starting class, None->light, light->medium, medium->heavy, heavy->extra class skill
+5ft move speed, 2 max
extra cantrip, 2 max
1st level spell once per long rest, 1 max
2nd level spell once per long rest, worth 2 trait slots, 1 max
advantage and resistance vs diseases and poisons
+1 HP per level, 1 max
sentinel rest: long rest is only 4hrs(1hr of light activity) and you are aware while you "rest,
resistance to one type of damage that is not bludgeoning, slashing or piercing.
climb speed equal to walk speed,
swim speed equal to walk speed,
water breathing,
fly speed equal to walk speed, worth 3 slots.
burrow speed equal to half walk speed,
"negative traits"
-5 ft base speed, max 2
small,
light sensitivity, worth 2 negative traits