Always remember that pronunciations differ from region and region and there are different pronunciations which are equally acceptable. Often the pronunciation differs if you walk just 10 km.
It's true that you shouldn't speak too weird and be conscious of it. But if you are worried about every word before you speak it, it will become a stumbling block for you. What is important is that you should be confident and you should spell out.
A couple of words even if you mis-pronounce them won't matter. Everybody does it. A friend of youths from North may utter a word differently than you friend from the South West or the Coast.
There are certain words my friends speak differently. A friend to mine from India always pronounces Rose as Ros and not Roz. Tour can be Toor or Too-ar. The pronunciation of some words change every ten to twenty years and after a phase the old pronunciation again gets in vogue.
And then there are words like schedule that can be spokes as shedule or skedule, depending on the country or state you hail from. Both are acceptable universally. So if you are a learner just don't fret over pronunciation.
Consulting a dictionary is good but all the time if you keep getting worried over the pronunciation aspect, it will hurt your confidence and can confuse you, as there is no limit to debate over right or wrong pronunciation.
So no need to get worked up over it. Just get out of it and speak as it comes. Good luck.