Sorry, don’t want to heap on the confusion, but I think part of the problem is the subtle differences between the four conditional forms in Japanese. S1たらS2 is specifically used when S1 and S2 occur in chronologial order – that is, S1 is the antecedent, and S2 is the subsequence. “(If/when) S1 happens, THEN S2 happens.”

勉強したら私は薬と日本語を勉強します。
If I study, I will study medicine and Japanese.

Here, your act of studying in general and your studying medicine and Japanese specifically occur concurrently, so you can’t use たら. Instead, you’d probably use 勉強するのなら, which could be rendered in English as “if I were to study”.

勉強するために教科書を読みます。
In order to study, I will read textbooks.

This looks fine.

バレンタインデーだったら僕は独りです。
When it’s valentine’s day I will be alone.
バレンタインデーだったら僕は一人です。
When it’s valentine’s day I will be alone.

Again, you’re talking about two events that are ocurring concurrently. It’s a little odd to use a conditional here anyway, even in English. You’d probably say バレンタインデーで、私は一人です – “on Valentine’s Day, I’ll be alone.”

１２じだったら私をねます。
When it’s 12 o’clock I will sleep.

This sentence looks fine, except it’s 私が or 私は – you’re the subject and/or topic, not the object. A little late to sleep though. You know what they say: early to bed and early to rise makes a man healthy, weathly and wise. =P

１２じだったらを僕は寝に行きます。
When it’s 12 o’clock I will go to sleep.

It’s really tempting to translate “going to (verb)” as に行く, but take care, here – に行く specifically means “go to (a place) for the purpose of (verbing)”, but that’s not the same as “going to (verb)” (which tends to be more like “I intend to (verb)”). 寝る on its own already conveys a meaning equivalent to the English “go to sleep” anyway.

バレンタインデーのはずはつまらないです。
I expect valentine’s day will be boring.

This says “My expectation of Valentine’s Day is that it will be boring”. It’s… ok, but a shade odd, I think.

Let me know if I can explain anything better. Honestly, sometimes it’s better to get confused and have someone explain what’s going on – it can help you understand things much more deeply. Don’t give up on it. =)

It depends on the font. Some fonts have the hat, some don’t. When they appear in kanji, the volcano tends to appear at the top the character, and fins at the bottom, but when you’re just looking at the radical, there’s not really any way to tell.

Are you the sort of person for whom technical explanations of WHY things work are helpful? Because if you want to ask questions about stuff, I’m happy to explain things in excruciating detail. =)

Maybe there are… community language exchange groups, or something. “I’ll help you with Japanese if you help me with English.” I couldn’t really say, though.

But yeah, the cost of that particular course is one reason I’ve never been able to attend. I always had either the time availble to do it, or the money to afford it, but never both at the same time. Sad face…

座れ = Sit!
お手 = Paw! (literally Hand!)
伏せ = Down!
待て = Stay!
よし = Good! Ok!
来い = Come!
止まれ = Stop!

Mind you, according to one site I’ve read, people in Japan tend to command their dogs in English rather than confuse them with the differences in gendered language. 座れ, for example, is a fairly brusque, masculine imperative form – a woman would prefer to say 座りなさい.

きて and おいで are gentler than the imperative form.

Ooo, Sydney. Which side? Eastern suburbs, here. =)

The suggested correction is correct. つもりだのあと is… particularly weird. =P

A lot of grammar structures in Japanese tend to be backwards to how we’d expect to see them in English – as Koichi puts it, try to think in Yoda-speak a bit. So where in English we’d say “we’ll do A after we do B”, in Japanese it’s more like “After B is done, then A”. Note the first clause in that pseudo-example is in past tense.