In blackjack, the house edge over an inexperienced players is around 2% [source]. Thus any small rule-adjustment will do the work.

My suggestion is not to change the rules but to simply remove half of the 2-6 from the deck. Card-counting players are waiting for exactly this situations, known as hot-deck, then they know that they have the edge over the house thus they shift from 1$ bets into 10K$ bets.

To put it simply, if cards of smaller ranks (2, 3, 4, 5 and 6) are
dealt and removed from the deck, their removal will have a positive
effect on your expectations. In other words, their removal increases
your advantage. As for the cards of higher ranks (10, J, Q, K and A),
their removal has a negative effect on your expectations. It simply
means that odds of creating a blackjack hand when these cards are
removed from the deck for the player are lower. Finally, the removal
of 7, 8 and 9 has almost no effect on your expectations.

EDIT: removing all of the 2-6 is too big of an advantage, I think it is better to remove just half of the 2-6. This is because removing all of the 2-6 will create wired situations where players almost know that the dealer will go bust.

Other rules-adjustments that can move the edge to the players:

1. Players win ties.
2. Dealer stand on 18 instead of 17

Suggestions from a variant called Player’s Edge 21:

3. blackjack payouts to 2:1
4. Two suited and ranked player face cards are an automatic winner. This includes beating a dealer blackjack.
5. Late surrender is allowed.
6. The player may double at any time. This includes on any number of cards, after splitting, and after doubling. The maximum number of double per hand is three.
7. Re-splitting aces allowed.
8. A player 21 always wins.
9. Player blackjack beats dealer blackjack.
10. Player may hit and double down after splitting aces.
11. Player may surrender after doubling, known as “double down rescue.” The player forfeits an amount equal to his original bet.
12. A five-card 21 pays 3 to 2, a six-card 21 pays 2 to 1, and a seven or more card 21 pays 3 to 1.
13. A 6-7-8 or 7-7-7 of mixed suits pays 3 to 2, of the same suit pays 2 to 1, and of spades pays 3 to 1. These bonuses pay after splitting but not after doubling.
    Suited 7-7-7 when the dealer has a seven face up pays $1000 for bets of $5-$24 and $5000 for bets of $25 or over.