high pressing - all your players will press any opponent player all over the pitch, even your ST will press oppo Defenders
Low press - your player will only press the opponent when they enter your own half of field
man to man marking - your player will select one opponent to be marked, they don't mark other player after decide one player, riskier if your player is weaker in strength/speed/etc and may lost the one on one battle, and other player will not support after one of your player lost the one on one
zonal marking - all the player will mark any opponent that enter to their zone
High pressing and man to man marking will tired your player fast, low fitness player will make your team always concede in last minute
remember only use man to man marking if each of your defenders is stronger than opponent attackers.
if you play defensive mentality, i bet you will put many defenders, so play high pressing will be not effective because you don't have enough man to press all over the field especially at opponent half side.
the more defenders you use is the more difficult to make offside trap success.
if you play defensive mentality with many defenders, the only way for you to score is through counter attack, and long pass will make your counter faster,
but that doesn't guarantee you to score because your chance created for scoring is very less since you not possess the game