Note that all examples in English don't mean that the vocabularies of the Phonetic Language will include English vocabularies!
Nouns are the most concrete words which people can understand easily. No noun of this language will have any gender. For example, "a boy" and "a girl" will be called "a masculine child" and "a feminine child". This will also reduce the number of vocabularies. The second problem is the plural. In Esperanto, there isn't the problem like in English(apples but candies and addresses) because its nouns end all with "o". But it is even easier with the word "several". So, "apples" will be "several apple"(<It is NO CORRECT ENGLISH anymore!).
But, the problem is how to make a word which can be understood easily. In this language, building words for musical instruments or animals are easy. But what can be the words for abstractive things e.g. "opinion" or "society"? Thinking about the ethmology, (have a look at the ONLINE ETYMOLOGY DICTIONARY) opinion means "what one thinks"(dictionary.reference.com/search?q=opinion). The verb "think" would can be imagined clearly. Maybe you think about the "Thinker" by Auguste Rodin. If we think about the possible "sound" we can hear from the person, it can be a grunting. But because we also need a word for "grunting", we can't take that sound for "thinking". It's a similar problem old Chinese people had at making their logographic characters which are in use till today. When we take the letter 意 (a deep thought, meaning), this contains tho parts(radicals): 音(muffled voice, sound) and 心(heart, mind). So, muffled voice + mind make the deep thought. We can make words here in a similar way!
After making some words, it will be easy: we should use already existing words to make new, more complicated terms. It will also make learning the language easier. In order to prevent making too long words at the end, basical words should be as short as possible.
Often when you look at the etymology of a word, we find a noun or a verb. We should make either a noun or a verb, which is easier to understand. "To think" is better than "thought", but a "building" is easier than "to build"(because of the abstract difference between "build" and "make"). For "to build", we can say "make a building". For "thought", we can say "thinking" or "a thing to be thought". The difficulty of changing a noun to a verb or a verb to a noun is that we have to choose the right way for each word. E.g. in English we have the postfixes "-ing" and "-ion" to convert a verb t0o a noun.
Adjectives and Adverbs
In English, e.g. "clear" and "clearly" are forms of the adjective and the adverb of the same meaning. It would be far easier to have the same form. Who won't understand the GRAMMATICALLY WRONG sentense: "The extreme large building was serious damaged by the hurricane."