Speaking just in terms of what will increase your visuals, nitrous will do exactly that- for the duration of the canister and some time afterwards. However, they are also very more-ish in the sense that they provide a feeling of 'some great revelation is just a canister away'.
If you can restrict yourself to a few instead of going through like 20 or so then they will certainly improve your visuals without making you fiend too much. Or you could just dose higher as others have suggested. Definitely meditation too. Sometimes i feel like nitrous is sort of a short term cheat method to see what practice at meditation long-term can provide.
Having said all that, i never trip with nitrous nowadays because i'm not looking for that level of intensity. But if you want spectacular visuals it will 100% provide them.
