How to say 'more' in various contexts

The way it was explained to me, więcej can be used for 'more quantity' and 'bardziej' as 'more size', but the use seems inconsistent to me in real life. If I'm getting almonds at a kiosk, and the seller scoops a bit, but I want a more, do i use więcej? Someone pours me some water but i want more? Someone cuts me a piece of cake but I want more? If i want to say I now make more money? If I want to say that want more optimism from you? People in France are more elegant? The ice here is more slippery? I am more sick?

In real life I keep finding myself being corrected, not understanding the logic.

"więcej" is used for "more" in any context - both for size and for quantity. Chcę więcej migdałów, więcej wody, więcej ciasta, zarabiam więcej pieniędzy.

It becomes interesting with the optimism questions. If I literally want MORE optimism from you - chcę, żebyś miał więcej optymizmu.

BUT if you want the other person to be MORE OPTIMISTIC, you would say - chcę, żebyś był BARDZIEJ optymistyczny.

And here's the rub - "bardziej" is used to compare adjectives, with "najbardziej" being the superlative form.

So, you would say: Francuzi są bardziej eleganccy, lód jest bardziej śliski, jestem bardziej chory.

Of course, you also need to remember that not all adjectives are compared this way:

mały - mniejszy - najmniejszy

długi - dłuższy - najdłuższy

but

interesujący - bardziej interesujący - najbardziej interesujący

krzepki - bardziej krzepki - najbardziej krzepki

Thanks Magdalena!

Would it sound awkward to always use 'bardziej' rather than the comparative form of adjectives/adverbs? i.e. "Bardziej długo" rather than "dłużej".

The distnction between wiecej and bardziej lies along the line between być (to be) and mieć (to have). One can mieć więcej and być bardziej. So you must always ask yourself if you are talking about attributes (something is ..., something is like...) or possesions (something has ..., someone wants to have more...). You use bardziej for attributes and wiecej for possesions.

Cinek

For example, your Polish teacher gives you a very specific assignment to do, with the final proviso "Nic więcej!", meaning "Nothing more (.... than what I've assigned). Or "Coraz więcej ludzi jest (here: NOT "są") bezdomne." = More and more people are (rather than "is"!!!) homeless. etc.

Make sense?

How I understand it is that Więcej is used with nouns, and Bardziej with verbs, adverbs and adjectives.

yeah, it would sound pretty awkward - some people would have trouble getting grasp of you mean


pam's advice is perfect AFAICT

nouns - więcej
adverbs and adjectives - bardziej

As it comes to verbs, you could use both depending on the verb - więcej to describe more quantity (Powinnam więcej ćwiczyć. - I should work out more.) and bardziej to describe the quality/attitude/feelings (Powinnam bardziej się starać. - I should try/strive to do sth more.)

You'd say:
Jeżdżę więcej od ciebie. - I drive more than you do.
but e.g.
Kocham bardziej od ciebie. - I love more than you do.

Nice round off to the other explanations, lunacy:-)
Thanks!