Here is my recommendation for those of you who want to get started in building up your faith by speaking in tongues. It’s very simple. Pray in tongues as much as you can. If you have the time, pray for an hour, pray for five hours. I find personally, that I begin with about 30 minutes and suddenly I hit a spring of living water this brook. It begins to just bubble forth. This is where I begin building myself up in my most holy faith, praying in the Spirit. How much should I pray? The more you pray in tongues, the more you will feel like praying further. I believe at least thirty minutes is needed for us to prime the pump and prepare the way for an explosion in our spirit of joy unspeakable and full of glory. Begin to pray in tongues daily, even if it is only for fifteen minutes. Gradually increase the amount of time you pray in the spirit. If you pray in the spirit, the language of glory, faithfully and consistently for 40 days, you will see a big change in your life, a metamorphosis like that mentioned in Second Corinthians 3: 17-18: “Now the Lord is the Spirit; and where the Spirit of the Lord is, there is liberty. But we all, with unveiled face, beholding as in a mirror the glory of the Lord, are being transformed into the same image from glory to glory, just as by the Spirit of the Lord.” One thing is certain, after this time of praying in tongues you will be stronger in your spirit than you were before.
Just as our physical bodies need water every day to survive, so our spirits need the life-giving spiritual water of the Holy Spirit every day in order to thrive. The more water we drink, the healthier we are physically. By the same token, the more of the Holy Spirit we “drink,” the healthier we are spiritually. The baptism of the Holy Spirit enables us to drink freely of the Spirit, not just tiny sips but great draughts of refreshing living water. After only three days without water the human body begins to shut down and approaches death. In the same way, people all around us are dying without the supernatural water of the Holy Spirit. Jesus said, “If anyone thirsts, let him come to Me and drink.” That is a very simple invitation, yet there are so many people who do not accept it simply because they do not know that they are thirsty.
From the book "The Hidden Power Of Speaking In Tongues"