The poetic language of these verses is rich. In verse 5, David is asking God to part the heavens and touch the mountain so that they smoke. Is David literally asking God to show Himself so that a literal mountain will smoke with fire? I don't think that's the point. Therefore, I do believe David is being figurative in his language in these verses.
Asking God to "smoke the mountain" in effect is asking Him to make a significant difference in our lives that is obvious to everyone around us. Remember, David himself had to deal with a lot of warfare. Therefore, David is asking God in effect to get involved in his battles, ultimately for His victory. This is why in Verse 6 David asks God to send lightening bolts to scatter his enemies.Then in verses 7 and 8 David asks God to rescue him from his enemies.
At times, we all have to face battles. We may draw upon a God to guide us to victory in the sense of His will getting done through us. Does this mean we win all the battles we face in life? That was not the case for David and is not true for any of us. Since God is all knowing, He already knows the outcome of those battles and therefore, we don't have to worry about what will happen. Back in verse 1, David realized it was God who ultimately prepared him to battle, and now in these verses, David in a colorful way is asking God to guide him through his battles.
Personally, we must acknowledge God is ultimately in control and He wants to guide us through whatever we are dealing with at the moment. No situation is too big or too small that we can't turn the outcome over to Him.
In this text, David is asking God to reach down from heaven and control the outcome of his battles. If God knows all things, why do we ask Him to control the outcome for our benefit? In other words, why do we ask Him to let us win and in effect let someone else lose the battle?
First of all, God knows all things but we don't. Therefore, it is OK to ask God not only to take over a situation but also to guide it based on our desires. Remember that prayer is about getting His will done and not our will. Since we don't know God's will, it is acceptable to ask Him to guide our battles as we desire.
Think about a literal military campaign. Good soldiers must obey orders. After a war is over it may be possible to discus whether or not those specific orders were appropriate. In the meantime, one must follow the chain of command. With God, we ask Him to sort out the details of the battle as we must obey Him (that is live by the principals taught in His word) and obey those whose command we are under.