Translation Guides

A good tip is to familiarize with normal speech patterns and colloquialism in Japanese, since you'll be mostly translating speech bubbles. Watch some Jdramas! They are really interesting and can introduce you to some current words and slang! And knowing your kanji is very helpful as well.
Here are some sources that I sometimes use when translating!
Sound Effect Dictionary
Another SFX Dictionary
My Favorite Dictionary♡
Kansai-ben Dictionary
Another Dictionary
Learn some Kansai-ben!!
Picking the right words can be difficult! ;D
This maybe helpful if you're sometimes unsure
English sound effects dictionary because English is a bit lack in that area
More SFX! ヽ(*⌒∇⌒*)ﾉ::･'ﾟ☆
Even more SFX! ｡:+.゜ヽ(*′ω`)ﾉﾞ｡:+.゜

I'll add more references, if I come across some more!

How to Format Translations
I'm a proofreader, so of course, I've seen a lot of different translation techniques. Understand that your translations go through a proofreader, typesetter, and sometimes a QCer.

Keys:
One critical thing to do is make a key for text indicators. Example:

You don't have to use these exact symbols, but keys are very important for the typesetter and the proofreader. Some translators use keys like "Box 1:"
Example:

note: I edited the image above to suit this purpose and added text.

One obvious thing: Mangas are from RIGHT TO LEFT, top to bottom. So that's how you should translate. Also note that proofreaders have to check for missing translations, so please make it easier for us by separating each panel. 

Example:

note: I edited the image above to suit this purpose and added text.


The information at the top of the page about the translator is optional but useful. It's also best to clarify things for the typesetter, like differentiating between small text and small text in bubbles.

Also, add a space between the text indicator ( [], "", ST, etc ) and the translation. It's easier to copy and paste for the typewriter, but one space is fine.

TNR vs TN:
Translator's notes, but TNR is included in the manga for clarification. Like, if you mention a Japanese food with no read translation in English, it's easier to leave the food in Japanese and make a TNR describing what it is. But you don't have to add TNRs to everything.

Additional tips:
~At least follow the rules of basic English grammar. It's tedious to force the proofreader to add punctuation or capitalization every single time. If you forget a few times, that's fine...but it's annoying when the whole document is written with no regard to grammar.
~It's helpful if you add multiple choices for confusing translations. If something doesn't translate smoothly or doe sound right, add a TN with an explanation. ie. TN: What he means is, he's tired of trying so hard. This can also be "I'm done with you" or something really harsh and blunt.
~If you're asking yourself whether or not to clarify...clarify. Proofreaders can always delete useless clarifications.
~You don't have to use my key specifically, but when you are making a key, make it as clear as possible.
~Everyone has their own style, so find the style that's most comfortable for you.
~Adding the correct page numbers is important! But make sure the page numbers correspond to the numbers of the raws. Like, if the raw is labeled "Page 56", then make the page in your translation "page 56".
~ TRANSLATE EVERYTHING. Even "Ah!" or "!!". 

Thanks! Is it okay now?