1. tone marks are only placed on the vowels:
                          a     o     e     i     u   ü  (more info on ü)

2. a and e always take precedence over all other vowels (note: a and e are never together in the same syllable.)

      Using second tone as an example.                          
                         ái, áo, uá, uái, uáng, üán
                         éi, ié, uéng, üé

3. when o and u are together, the tone mark is always on o

                        óu, uó

4. For all other cases, the tone mark is always on the final vowel

一杯果汁 yībēigǔozhī (a cup of juice)
一台電腦(电腦) yītáidìannǎo, 一部電腦(电腦) yībùdìannǎo (a computer)
一台車(车) yītáichē, 一部車(车) yībùchē, 一輛車(辆車) yīliàngchē (a car)
一條(条)船 yītiāochuán， 一艘船 yīsōuchuān (a boat)
一件外套 yíjiànwàitào (a jacket), 一件行李 yījiànxínglǐ (a piece of luggage)
一根頭髮(头发) yīgēntóufā (a strand of hair)
一棵樹(树) yīkēshù (a tree), 一朵花 yīdǔohūa (a flower), 一束花 yíshùhūa (a bunch of flowers)
一扇門(门) yīshànmén (a door), 一扇窗 yīshànchuāng (a window)
一條皮帶(条皮带) yītiáopidài (a belt), 一條(条)蛇 yītiáoshé (a snake)
一隻猫 yīzhīmāo (a cat), 一頭牛 yītóuníu (a cow)
一匹馬(马) yīpīmǎ (a horse), 一尾魚(鱼) yīwěiyú (a fish) (very formal, usu. 一條魚(条鱼) yītiáoyú)
一枚戒指 yīméijìezhǐ (a ring)
一副眼鏡(镜) yífùyǎnjìng (a pair of eye glasses)
一本書(书) yiběnshū (a book)
一雙(双)筷子 yīshūangkuàizi (a pair of chopsticks)
一份菜單(单) yīfèncàidān (a menu)
一張面纸 yīzhāngmiānzhǐ (a tissue paper), 一張(张)床 yīzhāngchuáng (a bed)
一片麵(面)包 yipìanmiànbāo (a slice of bread), 一片光碟 yipiànguāngdié (a CD or DVD)
一片樹葉(树叶) yīpiànshùyè (a leaf)
一篇文章 yīpiànwénzhāng (an article)
一把傘(伞) yībǎsǎn (an umbrella), 一把梳子 yībǎshūzi (a hair brush)
一套沙發(发) yītàoshāfā (a set of sofa)
一道菜 yīdàocài, 一盤(盘)菜 yīpáncài (one dish)
一座山 yīzuòshān (a mountain)
一棟大厦 yīdòngdàshà (a building)
一盞燈(灯) yīzhǎndēng (a lamp)
一顆星星 yīkēxīngxīng (a star)
一粒米 yīlìmǐ (a grain of rice)
一床棉被 yīchuángmiánbèi (a comforter or quilt)
(for simplicity, “一”  in first tone: yī)

Coming soon: how “一”, one, (yī, yí, yì) switches tone.

• listen or watch Chinese talk shows, news reports, drama or songs through radio, mp3, TV, movies, etc.; always have them in the background if possible. (with the internet, these programs are readily available online)
• shadow or follow along the program out loud (when there is only you and Fido)
• sing Chinese songs
• whenever you are with a Chinese speaking person, switch to Chinese as if you don’t speak English
• if you want to know how to say a certain word or phrase in Chinese, ask the Chinese person: qǐngwèn {english word} zhōng wén zěnme shūo? Excuse me, how do you say {english word} in Chinese?
• make sure you have high quality tools:  a good dictionary is a MUST
• carry a dictionary with you wherever you go; try to imagine that you need to communicate with a Chinese person and look up all the new vocabularies
• create paper or electronic flash-cards of words or phrases to test yourself.  (for example: you can do this while waiting in line)
• if you have a friend or family member that is also learning Chinese, speak to each other in Chinese
• talk to yourself, describe what is happening in Chinese (do it at your own risk when others are around)
• think in Chinese, dream in Chinese

When sounding out Pinyin,       j          q          x          y    can only be combined with ü, never u.  But when spelling Pinyin, these 4 initials will change ü to u, but it is still pronounced ü. 

That is why we only see:  ju       qu       xu        yu  (but they are pronounced: jü, qü, xü, yü).  Some people confuse the first three combinations with :  zhu     chu    shu

Most Chinese Pinyin input method uses the v key on the keyboard to represent ü.

不論故事聽起來有多動人….No matter how moving the story is, never forget that you are an interpreter.  No more, no less.  You become the person you interpret for (a witness, a prosecutor or an attorney) and that in itself is already very demanding and taxing.  You are not to add, delete or embellish what is being said.   You play a very important role of getting thoughts across accurately, but you remain neutral and invisible during this process.  You are not to judge, to form an opinion or to come to a conclusion about the case throughout the entire interpreting process.  A professional interpreter accurately pass on exactly what is being said and expressed.  You should however, be a constructive judge or critic of your work and always strive to be a better interpreter.

Example: 
nǐ hǎo
你好

Next time when someone says 你好 nǐ hǎo. Pay attention to the 你 nǐ， it becomes ní.

I can go on and on about the rules and exceptions of the third tone.  This is just the very basics that you’ll need to know for now.