As far as I know, when conjugating the verb for the I pronoun you will use ю or у. I was wondering if there was a trick to knowing when to use which one.
я читаю — I read
я живу — I live
Another way to know is to first identify if the verb is 1st or 2nd conjugation. 1st conj verbs have -ешь, ет, -ем, etc. 2nd conj verbs have -ишь, -ит, -им, etc.
For most 1st conj verbs remove the -ть -ти of the infinitive. If the resulting (present tense) stem ends in a vowel add -ю -ют: читаю, делают, теряю, теряют, старею, стареют. There are some high frequency 1st conj verbs that require altering the present tense stem, but once the alteration is made the same rule applies: советовать - советую, жевать - жую, петь - пою.
If the present tense stem (of 1st conj verbs) ends in a consonant, then add -у, -ут: иду, пишу, беру. There are a handful of mostly low frequency exceptions.
For all 2nd conj verbs remove the ть of the infinitive and whatever vowel precedes to find the present tense stem. For 2nd conj verbs the endings are -ю, -ят (говорю, стою, говорят, стоят unless the stem ends in a husher, then the spelling rule applies: получить - получу, получат, спешить - спешу, спешат
-ю normally indicates a verb stem ending with a soft consonant (in case of читаю it is читаj-). -у indicates a verb stem ending with a hard consonant.
However, it not always works this way. Zaliznyak grammatical dictionary (online version) identifies some regular patterns that may help you to figure out how to form 1st person singular:
Also, there are some irregular verbs and small groups of verbs that follow some specific conjugation patterns, so the best way is to check all personal verbal forms for each particular verb at Wiktionary.
Verbs with infinitive forms which are similar can have non-past endings for 1st person singular and 3rd person plural forms which are not the same; note verbs such as бросать (бросают), сосать (сосут), писать (пишут). Most grammars approach this difference by explaining that many Russian verbs have two underlying stems, a past stem and a non-past (which includes the perfective future forms) stem which must be learned for each verb. This disparity results from underlying historical processes. Another approach is to postulate that verbs have a single underlying stem (single-stem approach introduced by Roman Jacobson) whereby the final form is produced using a series of rules which alter the initial state of the stem and ending. Structurally, the latter approach is the most interesting with respect to understanding better the nature of the Russian verb system; however, there are pedagogical issues associated with this approach. (http://www.lesbaileyev.com/Project/cssRFindex.html)