Many native speakers pronounce /t/ as a very quick "tap" when it's between two vowels. However it's lighter than a clear /d/: "Writing" and "Riding" are pronounced differently in US English, with a stronger /d/ in "riding". This is quite hard to distinguish for learners, so unless you're confident I suggest using a clear /t/, or people may misunderstand you. The /r/ is pronounced in most US English, and is common the northern UK as well. You may choose to pronounce it or not, it shouldn't affect people's understanding of you.

British people pronounce "t" (better, bottle, water, ..) but American people usually say "d" .

in British accent the word "Better" is pronounced with stress on 't' (clear 't') and 'r' is faintly pronounced or almost not pronounced at all; However, in American accent 't' s(in "Better") are pronounced like 'd' and 'r' is pronounced strongly.