Psalm 18

The context of this psalm is David's thankfulness to the Lord on this day when he was delivered from Saul and his enemies.

"And he said, I will love thee, O LORD, my strength." -Psalm 18:1

“I will love thee, O Lord.” With strong, hearty affection will I cling to thee; as a child to its parent, or a spouse to her husband. The word is intensely forcible, the love is of the deepest kind. “I will love heartily, with my inmost bowels.” Here is a fixed resolution to abide in the nearest and most intimate union with the Most High. -Spurgeon's Treasury of David

He begins with metaphors that flesh out David's perception of the Lord,  defining Him as his rock, fortress, deliverer, strength in whom he trusts,  buckler, horn of salvation, high tower.

Psa 18:2  The LORD is my rock, and my fortress, and my deliverer; my God, my strength, in whom I will trust; my buckler, and the horn of my salvation, and my high tower.

“My strength.” Our God is the strength of our life, our graces, our works, our hopes, our conflicts, our victories. This verse is not found in 1 Sam 22, and is a most precious addition, placed above all and after all to form the pinnacle of the temple, the apex of the pyramid. Love is still the crowning grace.  -Treasury of David

There is something freeing and faith-filled in the emphatic "I will" constructions of this psalm.

Psa 18:3  I will call upon the LORD, who is worthy to be praised: so shall I be saved from mine enemies.

The situation David faced:

Psa 18:4  The sorrows of death compassed me, and the floods of ungodly men made me afraid.
Psa 18:5  The sorrows of hell compassed me about: the snares of death prevented me.
Psa 18:6  In my distress I called upon the LORD, and cried unto my God: he heard my voice out of his temple, and my cry came before him, even into his ears.

God is portrayed in the middle section of this psalm with an anthropomorphic Greek God kind of flavor:

Psa 18:8  There went up a smoke out of his nostrils, and fire out of his mouth devoured: coals were kindled by it.
Psa 18:9  He bowed the heavens also, and came down: and darkness was under his feet.
Psa 18:10  And he rode upon a cherub, and did fly: yea, he did fly upon the wings of the wind.

More beautiful imagery of His rescue:

Psa 18:16  He sent from above, he took me, he drew me out of many waters.

Psa 18:19  He brought me forth also into a large place; he delivered me, because he delighted in me.

Trusting in the perfection of His plan:

 Psa 18:30  As for God, his way is perfect:

Rom 12:2  And be not conformed to this world: but be ye transformed by the renewing of your mind, that ye may prove what is that good, and acceptable, and perfect, will of God. -KJ

Rom 12:2  Do not be conformed to this world, but be transformed by the renewal of your mind, that by testing you may discern what is the will of God, what is good and acceptable and perfect. -ESV

By faith, David also understood the nature of the Lord and how He revealed Himself to mankind. God rewards people according to their inner character: faithfulness to the faithful (ḥāsı̂ḏ, related to ḥeseḏ), blamelessness to the blameless, purity to the pure, but shrewdness to the crooked (‛iqqēš, “twisted, perverse,” a word also used in Psa_101:4; Pro_2:15; Pro_8:8; Pro_11:20; Pro_17:20; Pro_19:1; Pro_22:5, “wicked”; Pro_28:6). His dealings are always just. -Bible Knowledge Commentary

"The predominant thought throughout these verses is that David attributed every ability and victory of his to the Lord. Everything he had done and everything he now enjoyed was due to the Lord’s enabling." -BKC

Although God is subduing David's enemies, it's interesting to met hat he mentions God's gentleness to David:

Psa 18:35  You have given me the shield of your salvation, and your right hand supported me, and your gentleness made me great.