According to Philippians 4:4-8 we are to Pray Always.
Starting with verse 4) "Rejoice in the Lord always: and again I say, Rejoice. (v5) Let your moderation be known unto all men. The Lord is at hand. (v6) Be careful for nothing;
(v7) And the peace of God, which passeth all understanding, shall keep your hearts and minds through Christ Jesus. (v8) Finally, brethren, whatsoever things are true, whatsoever things are honest, whatsoever things are just, whatsoever things are pure, whatsoever things are lovely, whatsoever things are of good report; if there be any virtue, and if there be any praise, think on these things."
Angels only respond to the Word of God according to Psalm 103:20. "Bless the Lord, ye his angels, that excel in strength, that do his commandments, hearkening unto the voice of his word." When we pray the scriptures, speaking the word of God, we are guaranteed a response. We are also guaranteed that God hears all our prayers and supplications for others especially when we offer them up with thanksgiving. Just a little encouragement to be confident to pray always because God hears your prayers and will answer. Read these verses: 1 John 5:14, Hebrews 4:16, Proverbs 15:29, Psalm 18:6 and John 16:24.