Learning a language is a long journey. Just think about how long it takes kids to master their native language. Years and years of lessons and practice. Do NOT fall for “Beginner to Fluency in Three Months”!
Once you start, keep at it. Imagine going to the gym to get fit. If you stop doing it after a while your improvements will wane, and eventually dissappear if you stop long enough.
Practical & Systematic
Adults and children learn differently. Analytic thinking will inevitaly come into play if you are older and already speak one language.
While kids might pick up a language by being just around speakers of that language, most adults will benefit more from a practical yet systematic approach to learning.
Look for teachers who have had experience learning a foreign language themselves. They will probably have a much better understanding of the difficulties you might encounter.
Non-native teachers with a high level of proficiency and sufficient teaching experience may be a blessing, because one of the essentials of good teaching is language awareness, which most native speakers lack unless they have studied their native language in some way.