You will find quite a bit of repetition of you read through a few other lists in the forum.
20 Temple Guard for the Slann will be very nice.
Next fill up your core choices. Two blocks of Saurus and several units Skink Skirmishers
(the latter are to help you deal with large T targets).
Two units of Chameleon Skinks to deal with Warmachines first and large T targets second
Salamanders to whittle away at those large enemy blocks with T3
It will leave you with some points to fill in the holes. You lack a "hammer" unit to counter flank charges. Perhaps a Scar Vet to add some punch to your Saurus unit. A lev 1 priest with a scroll.
How you round out your army depends a lot on personal preferance and your own experience and gameplay.
Unltimately, the best advantage you have in Warhammer in knowing the enemy. When you build your army, make mental notes how you would deal with a gunline army or one filled with big monsters. You do that and the battle is half won already.
Good luck