basic tips on how to know when to keep or sell runes

[short solstice]

any basic advice on how to know if you should sell or keep a rune? i keep thinking "oh, i have a good support rune" but people say its not good, even though its like hp/acc/res, which i thought was good for support

[fair cobalt]

#1048710794373771326
#1065564506408882196

can ask when not sure abt a rune in #1084154772493447258

compare runes to ur inventory