Erica, master 'а'. It is fun:) Most of learners neglect it, because almost any idea can be expressed with 'но' and 'и'. But when a foreighner uses it his/her Russian instinctively feels more... more "our". More Russian.:) There is something very Russian about 'a'.

Russian и, а, and но cover the same range of functions as English and and or, but they divide it a little differently. и almost always translates as and, and но almost always translates as but, while а can translate as either. и typically relates two things that are alike, naturally related, sequential or simultaneous events, or anything else that seems to naturally go together. но typically has a sense of failed expectations or a contradiction. а is trickier, because it is a lot like и but instead of joining two similar ideas, it typically joins two contrasting ideas. It is especially common if you are comparing two people who do slightly different things: “John eats salad and Mary eats pizza.” This has the sense of and in English because you are making a list, but it is also showing a contrast. If you said “John and Mary eat pizza” then you would use и. In fact, а can actually introduce a change in topic. If you start a new sentence with и you are continuing the same idea, but if you start a new sentence with а, it might be to introduce a new subject (“And John arrived.”) and change in the narrative. (Introducing a new sentence, но would most likely indicate something unexpected or that directly contradicts what just happened, not just a new topic.) In a way, а might sometimes have the sense of English “On the one hand, but on the other hand…” — related but contrasting ideas. Of course if you think about it, English and and but are interchangeable a lot of the time, but with slightly different nuances. The same can be said for the Russian conjunctions.

https://russian.stackexchange.com/questions/201/what-are-the-different-ways-of-saying-but/

Задавай вопрос, а не делай запись, так тоже можно ответить, но не удобно. Pay attention to how "а" and "но" were used in my sentence and maybe you'll see the difference.