I think only compliment when you really mean it. I feel like I get too many compliments, and it's hard to tell which ones are the real ones and which ones are the fake ones, which means the real ones lose their value.
Also, when/if you compliment, don't overdo it, just be real, your compliments sound fine - eg. telling someone they're a reincarnated angel is overdoing it.
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Into the dark...