Save the left-handed serves for certain strategic moments since the opponent would acclimate if done earlier.
No one plays 1.d4 to avoid tactics but rather because they're in the mood for the kind of imbalances 1.d4 brings, wants to avoid the Sicilian and Berlin Defense or specific preperation against an opponent.
If he learns 1.e4 thoroughly then he'll have serious gaps against 1.d4. As white just setup a Torre attack and play c3 or c4 or even not move the pawn depending on the kind of position you'll end up in. As black the Queen's Indian will offer you experience with imbalances and plans you'll find against other systems like 1.Nf3 or 1.c4.
It has been three weeks. Out of curosity what have you done to learn 1. e4 e5? Do you have a line against the Spanish, Italian, Scotch, Four Knights, and Ponzini? Not to mention the Russian game and the Philidor. What lines or positions are giving you problems? What lines or positions do you like?
My guess is that he's done nothing but more lip flapping the last 3 weeks .