To recommend something in a friendly way, use you should + the base verb. Add really to make the advice stronger without sounding rude: you really should. Both point the listener toward an action you believe is good for them.
Recommending: should and really should
you should /juː ʃʊd/ — You should read the instructions before the test.
you really should /juː ˈrɪəli ʃʊd/ — You really should visit the new exhibit at Magaff Library.
Not ""You should to arrive early."" — say ""You should arrive early."". After should, use the base verb with no "to".
Try it: Mei: The app is ready for the demo, I think. Amina: You ___ test it again first. Which reply is firm but friendly, and correct? (really should / should to / should tested) Answer: really should — "Really should" strengthens the advice while staying friendly, which is exactly Amina's tone. "Should to" is wrong because should is followed by the base verb with no "to", and "should tested" uses the past form instead of the base verb "test".
Suggesting an option: consider
Consider means think seriously about an option. It softens a suggestion. You offer the idea rather than push it. Follow it with a noun or an -ing verb: consider the club / consider joining.
consider /kənˈsɪdər/ — Mei should consider joining the debate club.
consider taking /kənˈsɪdər ˈteɪkɪŋ/ — Diego considered taking a shorter route to Moshridge Business Park.
Not ""You should consider to join the club."" — say ""You should consider joining the club."". After consider, use the -ing form, not "to".
Try it: Lars: The venue is over budget. Any ideas? Sofia: The committee ___ a cheaper venue. Which reply is grammatically correct? (considered / considered to / considered to book) Answer: considered — Consider is followed by a noun ('a cheaper venue') or an -ing verb, so 'considered a cheaper venue' works. The other two add 'to', which does not follow consider. You would need 'considered booking', not 'considered to book'.
Sounding sure: definitely, I'm convinced, trust me
To push a recommendation with confidence, show certainty. Definitely makes an opinion sound sure. I'm convinced says you strongly believe it after thinking. Trust me asks the listener to rely on your judgment. It is informal, so save it for friends, not formal writing.
definitely /ˈdefɪnətli/ — The workshop is definitely useful for new students.
I'm convinced /aɪm kənˈvɪnst/ — I'm convinced the new schedule will help students.
trust me /trʌst miː/ — Trust me, the walk to Senfarrow Brook is worth it.
Not "In a formal report: "Trust me, this venue is cheaper."" — say "In a formal report: "I'm convinced this venue is cheaper."". Trust me is friendly and informal; I'm convinced fits serious or written contexts.
Try it: Wei: Does regular practice really help? Hiroshi: ___ that regular practice improves confidence. Which reply states a strong, reasoned belief? (I'm convinced / Trust me, / It's definitely,) Answer: I'm convinced — "I'm convinced" signals a strong belief reached through thought, which suits a formal recommendation. "Trust me" is too informal for a report, and "It's definitely," misplaces 'definitely' and breaks the sentence.