The first step you want to do is to list the phonemes of your language. You can find these at wikipedia.org/wiki/Help:IPA/English. Just change "English" to the name of your language in English (Japanese, Spanish, Indonesian, Norwegian, etc). I've made an English reclist before, so now I want to create an Indonesian reclist. I'm going to refer to wikipedia.org/wiki/Help:IPA/Indonesian.
Keep in mind that not all of the phonemes listed there is necessary. Sometimes there are marginal phonemes that appears rarely. Or there are phonemes that can be substituted with other phonemes (allophones). You can adjust the phonemes you want to include as you like.
The phonemes are written in International Phonetic Alphabet (IPA).
Here are the phonemes listed in the Indonesian page:
In Indonesian, x and h are allophones, and so ʔ and k, and f and v. So I'm going to discard x, v, and ʔ. For the vowels, e and ɛ, i and ɪ, o and ɔ, and u and ʊ are also allophones. So I'm just going to include one part of each pair. I'm also not going to use the dipthongs, I'll just replace them with two vowels if I need them later. With that modification, here are my final phonemes:
After we have the final phonemes we want to use, we need to transform the IPA symbols to X-SAMPA symbols. X-SAMPA is easier to write. You can find the conversion table here. Here are my phonemes after the conversion:
Before writing the reclist, decide on how many mora (syllables) you want to include in a line. A line is one recording file, and you need to record a line in one breath. So the more mora you have in a line will make it harder to record. But if you use too little mora, you're going to have much more file.
Keep in mind that one mora is reserved for the starting vowels. So the minimum mora is 2 in a line. I'm going to make a 4 mora reclist.
To split the mora, you can use -, _, or any separator that is not in your phoneme symbols. I'm going to use -.
Now we can start writing the reclist. Start with the first vowel, then go through each consonant. After you have 4 mora in the line, you have to make a new line. Here are my reclist for the first vowel:
Then we can just duplicate those lines, and replace the vowels. This will make it faster. With that, here is my final reclist:
Record each line in one breath and string them together. For example, read "a-ma-na-Na" as "ammmannnaNNNa". Don't quickly switch from the consonant to the next vowel. Hold the consonant a little bit longer so you have enough overlap for smooth transitions.
For consonants like p, b, t, d, k, g, tS, and dZ you can't hold it, right? So you'll just have a little bit of silence there. So "a-ba-da-dZa" will be like "ab bad dadZ dZa".
After you record the reclist, you need to create the oto file. I like to use the default value of overlap 50, preutterance 100, and consonants 150. But more about it on another article :)