It's the last year of your 30s, so make the best of it!
This is the last year of your 30s, so I hope you enjoy it!
It's the final year of your thirties, and I hope you'll treasure it.
「Make the best of it」は悪くはないですが、ある時に「やばい状態だけど何とかいい道見つかったらいいですね」というニュアンスがあります。気を付けてください。「I hope you enjoy it」はそういうニュアンスがないです。
例文3はユーモアを減ってもっと美辞麗句のようになります。
This is the last year of your thirties so enjoy it!
30代 - 30s, thirties
30代最後の一年 - last year of your thirties
大事に過ごす
Enjoy it
Treasure it
Make the most of it
Make the best of it
This is the last year of your thirties so enjoy it
This is the final year of your thirties, so make the most of it