Pentecostals believe in the Father, Son and Holy Ghost. they believe in the manifestation of the Holy Ghost through speaking in tongues(but not required to be saved). Salvation is through accepting Jesus Christ. Your life should reflect your relationship to Christ, but "Good Deeds",wearing long skirts and not wearing make-up DOES NOT make you saved and is according to your own conviction.Pentecostals are not isolated from other denominations but agree on a common ground that they are saved through Jeus Christ only, and are separated only by different ephasis.
"For by grace you have been saved through faith, and that not of yourselves; it is the gift of God, 9 not of works, lest anyone should boast" -Ephesians 2:8,9
Pentecostal Christians emphasize the day of Pentecost in the book of Acts.