Just by looking at the radical to tell whether it's onyomi or kunyomi.
They go by two systems
ONYOMI which is CHINESE READING. Onyomi means sound readings. Are multiple kanji combined into one. They are often called Jukugo which means they are the really big English words that smart people like to used all the time. Onyomi has no hiragana attached to the kanji and they have multiple kanji in them. For example 同様 (どうよう/douyou) means identical, equal to, same (kind),like, similarity.
Here's a break down of 同様
冂 (キョウ、ケイ/kyou,kei)=down box
All this adds up to 同様. All six kanji's make up one word. If you heard of a two for one sale this would be an example to help remember.
KUNYOMI is Japanese reading of kanji. you'll use kun readings when a kanji has hiragana attached to it or when a kanji's sitting out by itself. You won't find them when it comes to multi-kanji words as often.
For example, 赤 (あか/aka)=red is a noun with out the hiragana at the end and 赤い (あかい/akai) is used as an adjective with the hiragana at the end in Kunyomi. Along with 食べます、行きます、etc.
Also you should avoid writing you name in Kanji because most Japanese have a hard time reading and remembering kanji. Plus it will make your name sound strange and weird. Also believe it or not there are some that have a hard time telling part onyomi and kunyomi. It's shocking and unbelievable, but it's true. They also can still tell the Kanji character part by the Hiragana and katakana. Also you have to study the kanji characters one by one because they are used in many ways. This requires a lot of studying if you want to read to Japanese. Just focus on learning the systems in order start with Hiragana, katakana, and then kanji.
Try watching Japanese TV shows, dramas, interviews of your favorite singer's or actors, movies, and music. Gaki no tsukai you can find them on YouTube. YOSHIKI from X-Japan is also good too. Some of his nico douga interviews are on YouTube.You can find dramas on Viki and gooddrama. For the music go to jpopasia they have the hiragana, katakana, kanji, romanization and English translations. You can used apps like Memrise, Japanese for Android, Mindsnacks, Takoboto, Akebi,jisho, &ルルロロ (ruru roro) they are children's games and they can help study Japanese. Japanese YouTubers like KinoshitaYuka, HikakinTV, Keimushi-chan. For more help go to ejje.weblio.jp you can use both Japanese & English.
You'll also have to remember the Japanese system goes by Subject, object,& verb or SOV. For example, you how we say "turn on the bath water", they say "turn on bath water" it sounds like something a toddler would say, but this is actually the literally translation of what the sentence structure is saying. When you speak Japanese you are literally saying the meaning of the sentence. Here's another example.
“I went to England.”
イングランドへ行きました。(innguranndo he ikimashita). Here's the literally translation of it. "England to went"
"England" is your subject, "to" is your object, and "went" is your verb
Japanese say things in daily conversations literally. You know the game musical chairs this is a good example because Japanese play musical chairs too, but it's called "いすとりゲーム" (isutori-ge--mu) which mean "chair take game" in literal Japanese. In literal English it means "to take a chair away game". Translating like I just did in literal Japanese first and than translate it in English. It's a lot quicker that way and your level of Japanese will improve incredibly. Also there is the Adjectives can be a little tricky because some adjectives change to express negative or past tense. Since winter is almost here, I'll show you how to use Cold. You cold is 寒い (さむい/Samui) 今日は寒いです (きょうはさむいです=Kyou ha samui desu)=It is cold today, but if you’re talking about yesterday being cold, you would say 寒かった (さむかった/Samukatta) 昨日は寒かった (きのうはさむかった/Kinou ha samukatta)=It was cold Yesterday. If it’s not cold, you can say 寒くない (さむくない/Samukunai) 今日は寒くない (きょうはさむくない/kyou ha samukunai)=It is not cold today. Like verbs, these changeable adjectives are also agglutinating, which means you can add more to them. For example, 今日は寒くなかった。(きょうやきのうさむくなかった/Kyou ya Kinou samuku nakatta)=It was not cold today. This will take a lot of practice & time to get used to. Just think of like the board game scramble when you translate it into English. If you have Twitter, Skype, LINE, Instagram, or Facebook you can find Japanese friends on there. You can also ways put out a message here on Hinative asking if someone who is Japanese wants to chat on Facebook, LINE, Skype, Instagram,or Twitter that you want to chat in both Japanese and English. It's okay if you don't know much Japanese. You'll Japanese will improve quickly this way and you'll along the way what to say and how to write in Japanese. That's how I learn Japanese.You can also try Maggie sensei. She list everything on here website about the grammar and the particles.You can used apps like Memrise, Japanese for Android, Mindsnacks, Takoboto, Akebi,jisho, &ルルロロ (ruru roro) they are children's games and they can
Usually Japanese have Skype, LINE ,Instagram, or Twitter. Not many Japanese have Facebook. If your lucky that someone has Facebook then that's great. You can also try watching Japanese tv shows, dramas, movies, reading articles, blogs, & listening to Japanese music just to get some practice in. For the dramas you can go to KissAsian.ch, Goodrama, & Viki. Don't worry they already have the English subtitles installed with them. For the music you can go to Jpopasia. It has the hiragana, katakana, kanji, romanization, & English translations.