Recommended pronunciation of international English for foreigners

There are some differences in the pronunciation of English in USA and in UK. Furthermore, there are differences in the pronunciation in different areas of the same country. Examples: "go" is pronounced with /o/ in USA and /ə/ in UK. In USA, some areas have the cot-caught merger, other areas have the pin–pen merger and other areas has the Northern cities vowel shift.

Since I will not live in an English-speaking country, I will use English with people from different parts of the world, including Americans, British and non-native English speakers, such as French, Germans and Russians. Therefore, I need use a neutral or international version of English and I have no need to learn details of specific dialects.

Non-native English speakers do not have a dialect. My writing is messed, it mixes features of American English and British English in the same text. I learn English from different sources and the varieties became mixed in my head.

Do I have to follow the IPA in the dictionary totally? Can I choose some easier features from each dialect to make my own pronunciation? Is it strange to pronounce some words like someone from London and other words like someone from New York?

The English vowels are really difficult for me. I prefer the American vowels and the British consonants. The use of the cot-caught merger will make my life easier. The American "t" is strange and I prefer the British "t".

This issue has been dealt with by Jennifer Jenkins in her work on English as a lingua franca (ELF). She did studies to discover which elements caused the most confusion and which mattered less. In short, here's what she found:

1. There's little variation in consonant pronunciation among the world's major English dialects. ELF speakers should aim for the same pronunciation, but generally the so-called "th sounds" can be replaced by t/d or s/z. General American /r/ should be used. Avoid flapping the /t/ in words like letter. Aspirate /t/, /p/, and /k/ in initial positions (like tore but not store).
2. Do not drop consonants in consonant clusters (e.g., problem as /pabɜm/) or at the end of a syllable (e.g., top as /ta/). If you cannot produce these, it's better to add extra vowels (a schwa) in between or after than to delete consonants.
3. Vowel length is more important than vowel quality. This is not the difference between so-called long and short vowels (e.g., hop vs hope). Instead it's the actual timing length (e.g., hat vs had). The /ɜː/ vowel, as in girl or first, is also important. American or British vowels generally make no important difference.
4. In connected speech, meaningful breaks in tone units and the placement of nuclear stress are important.

Note that all of this is based on averages and tendencies.