For magical secrets, take counterspell and spirit guardians, counterspell is obvious while spirit guardians gives you a nice aoe dmg/cc option to deal with mooks, though you might get into risky situations until you are level 8 and got your feat when trying to utilize spirit guardians, regretabbly you are very squishy, if you dont like it you may try slow, it is a great debuff and it is friendly fire safe. You might even take shield spell tbh, I am strongly against Eldritch Blast without the invocation.

As for feat, if you take moderately armored, you go from studded leather AC13 to half plate+shield AC19 (+1 Dex from feat gets you 14 Dex) which is a HUGE leap, this will allow you to stay alive, maintain concentration, and it will even allow you to utilize Spirit Guardians if you take it, tbh as a DM you would not last 2 encounters with 13 AC on my table.