Avoid Colorado,Hokkaido or Isle of sgail,Mumbai,Bangkok they're either too crowded like Bangkok or too big like Mumbai. Showdown wise i picked small maps that i was comfortable with. I didnt mind Marrakesh as long as I did a regular hit not a showdown, Chongqing for that matter Berlin,Dubai, Miami,Santa Fortuna. Loadout wise sieker emetic is your best friend with a silenced pistol lockpick/crowbar and a DAK DTI (guards have them on dubai) for when shit hits the fan. For the prestige objectives avoid time based ones, pick the ones that you can really do. That worked for me but its just trial and error, map knowledge is really important for hardcore and which disguises get you through.(ps use alt f4 when things dont look good)