It is far more helpful to conjugate a small number of verbs correctly and automatically early in your language learning, than to have a large vocabulary and use it carelessly. For this reason, the learner should invest significant time mastering correct use of verbs at the outset, as this is one of the most valuable things he can do if he wants to speak correctly. As with many disciplines, it is far easier to acquire good habits at the start, than to unlearn bad ones later on.
Part of every language lesson should be spent conjugating verbs. For the student of most languages, but especially of Romance languages, regular verbs in the present, imperfect, perfect and future tenses are essential and should be mastered early in your language learning adventure. A thorough study of regular verbs, will stand the learner in good stead as he expands his vocabulary. If you are practicing these forms regularly they will quickly become second nature and you will find yourself using them quite naturally. If you are working with a teacher this is easy to do, but with a little effort the self-learner can also get a lot of practice by writing and review the verb forms himself, and by transforming sentences from one tense to another. It is not difficult to check your own work on this, and you will quickly build up confidence and know when you are unsure of the correct answer.
In many languages the most common verbs, such as 'to be', 'to have', or 'to do', are irregular and these require special attention so that you can use them correctly. The positive side of this is that they are also very common so that you will use them frequently and get a lot of practice. It is not necessary to learn all the irregular verbs at the start, so you can just focus on the common ones, or the ones that are specific to your interests and leave the others for later.
More complex tenses like the conditional and the subjunctive can also be set aside at the beginning, although it is important to recognise them when they are used. Both of these tenses exist in English, but we rarely use them consciously and English speakers often find it far more difficult to understand their proper usage than how to conjugate them. The beginning student should be introduced to them so that he can recognise them, but can leave mastery for a later stage.
In English we often use helping verbs such as 'going' or 'will' to convey variations of tense, but most other languages have particular forms to convey this. Some learners are lazy and do not bother to understand the correct application of tense, and this immediately marks them as foreigners even if their accent is impeccable. If you learn the forms early and practice using them correctly you will begin to think in the syntax of your language and you will find it easier to develop a good style.