Luke says that Jesus spoke a parable to teach us to always pray and not give up (Luke 18:1). Plainly stated. But easily forgotten.
Why do we give up praying? It mostly happens because most of our prayers are wishes only. Such prayers cannot be sustained.
Then there is the problem of no visible change in situation. Only when you know the mind of God and his will regarding that situation can you boldly and in faith hold on to God in prayer. See Elijah’s perseverance in prayer (1 Kings 18:41–46).
Again we give up praying because prayer demands alertness and watchfulness. Jesus himself said that the spirit is willing, but the body is weak (Matthew 26:41).
Above all, there are two enemies of prayer. Sin cherished in the heart will not get you an answer from God (Psalm 66:18). And disbelief. Often we keep on doubting even when asking (James 1:6). Soon you quit praying.
So what is the practical tip. Get alone with God as much as you can. And pray often. For prayer is the life- breath of a Christian. If you give up praying, you are as good as dead. Prayer is a vital sign of life.
The great encouragement in this parable is that Jesus reminds us that God is not unjust. So how much more will he answer prayer. But he ends the parable asking whether when he comes; will he find faith on the earth?
Without faith in the absolute authority of God over all; we easily give up praying. Do not give up. Keep on praying till he comes!