The Bible does teach of angels that minister to those who are the heirs of salvation. In speaking of children, Jesus referred to "their angels" (Matthew 18:10). Evidently, we have angels who have the special job of looking out for us.
However, there is no command or even need for us to identify them or know what forms they take. In fact, as long as they are in spirit form, we will not see them. It took a miraculous opening of the eyes for the young man with Elisha to see the horses and chariots of fire around them (2Kings 6:17). We are to focus on pleasing God, not His created beings (Proverbs 16:7; Colossians 1:10; 1Thessalonians 4:1; 2Timothy 2:4).
On those occasions when angels do make themselves visible to men, they look like any other men. The angels that appeared to Abraham when he was in his tent door looked like three men (Genesis 18:1-2). We find this throughout scripture. When the book of Hebrews refers to the possibility of entertaining angels, it says we would do it "unawares" (Hebrews 13:2). In other words, if you did meet an angel, you would not be able to distinguish him from any other man.
The bottom line is that we are told about the angels to encourage us. God has His created beings watching over us and caring for us. However, we are not supposed to be looking for them in any special way and we are not supposed to do special things to please them. They minister to us so that we may give ourselves to the Lord and serve Him.