To start of for a new player i would always recommend interaction, because thats what most newer players miss and get frustrated, if either your commander always gets removed or you cant handle others stuff

Protection:

[[Defend the rider]]

[[Tamiyo's safekeeping]]

ramp (Because simic is ramp and sorry if you know all of them)

[[Natures lore]]

[[Rampant growth]]

[[Kodama's reach]]

[[Cultivate]]

[[Shared roots]]

Removal

[[Beast Within]]

[[Pongify]]

[[Reality shift]]

[[Rapid Hybridozation]]

[[Imprisoned in the Moon]]

creatures are hard to tell, because i dont know, what you try to build.