I just read an article the other day about someone who was working towards learning French and had some interesting points regarding verbs. During her studies, she learned the present form of a verb first, then the past and future, then later on, the subjunctive. At each point, she had to stop and relearn the verb rather than learning it in a single package.
Honestly, this is what really frustrates me with learning modern languages. All of the materials seem to want to teach this way. You're always going back to a verb and having to essentially relearn it with more data.
Now, my case may be a little different than most. I started out my language studies with Latin in college and used the Wheelock book, which I still think is one of the best language studies books ever. I was taught to learn my verbs as a packet, like so with "to love": amo, amare, amavi, amatum.
What this actually does is teach the 1st person singular present, present infinitive, 1st person singular past and perfect passive participle forms all in one. I may not have known what or how to use the perfect passive participle at first, but by the time I got there, I had the form memorized for dozens of verbs. I could move forward immediately, without having to go back and re- memorize verbs because the relationship between the forms is not necessarily discernable. Those four forms allowed me to build verbs however I needed to. It was so easy.
But if you learn each tense separately, you're going to have to go back and relearn them at some point because modern books aren't usually going to go back and teach you the new form for all those verbs they've been showing you so far. Here's the thing. Without that past singular form, it is impossible to know how to conjugate most verbs, you can only guess.
In Latvian, there are three verb stems you have to know in order to build verbs in any tense: the infinitive stem, the present stem and the past stem. If you know all of these, you can do anything you need to do with verbs. They are built on the infinitive, 1st person present singular and 1st person simple past forms. Knowing the present and past forms also ensures you know which conjugation the verb falls in as well and you can conjugate it to your heart's content. (And should.)
So here's my way of doing things, brought over from Latin to Latvian. Learn verbs with the infinitive and 1st person present/past forms.
No, dictionaries won't list all the stems - they will only list the infinitive - so you need to use a spelling dictionary to get it going. But if you have those forms memorized, you will build atop your knowledge, not rip it down and start over every time a new tense is introduced.