Practice fluently giving a talk using common words and technical terms containing your problem sounds
Version #1: Choose on the left side of this Compleat Lexical Tutor page the “basewrd1” k-list. Highlight as many of these most frequent 1000 words in U.S. spoken English (based on the spoken section of the Corpus of Contemporary American English) as you’re interested in running through the North American English Pronunciation Highlighter. Click Ctrl + C to copy all highlighted words and then paste (Ctrl + V) the words into the North American English Pronunciation Highlighter, choose the problem sounds you want the highlighter to identify, and click submit. The highlighter will then provide at the end of its output a list of all words containing your problem sounds. Outline a talk or story that logically includes as many of these problem words as possible. Audio- or videorecord yourself giving that talk or telling that story. Then carefully watch/listen to your recording to check whether you pronounced your problem sounds correctly.
Version #2: Copy-and-paste a list of technical terms commonly used in your field (such as those included among the TEAM resources available from Michigan State University) into the North American English Pronunciation Highlighter in order to identify those containing your problem sounds. Then outline a talk that logically includes as many of these problem terms as possible and audio- or videorecord yourself giving that talk. Then carefully watch/listen to your recording to check whether you pronounced your problem sounds correctly.