For fluent speakers of any language, maintaining consistency with tense is a skill that's naturally acquired. The entire point behind utilising different verb tenses is that it enables us to be very specific when it comes to talking about when something occurred or will occur. Normally, there are two options for telling a story - the Simple Past Tense and the Simple Present Tense, but of course, no matter which you choose there will be times when you'll need to employ other verb tenses as well. Maintaining consistency with tense ought to be easy for anyone who's familiar with the language, but it's really choosing which tense might be appropriate for telling the story that can be tricky. For example, many amateur authors like to experiment with delivering a story in the present tense, or to blend both the present and the past tense together in the same way that they prefer to tell stories in the first-person, but will occasionally blend a first-person narrative voice with a third-person narrative voice in the same piece of writing.
Present tense writing gives a piece a sense of immediacy. It can be exciting because the reader feels as though he or she is actually in the moment, right there with the characters. But it's not really a natural way to tell a story because the reader isn't there, and because authors frequently need to mention things that happened at some point in the past and things that haven't happened yet, it can quickly get confusing for the reader if the time-frame for what the author considers the present in the story is "now, right this minute." It can be limiting and it can be confusing.
Take a look at how a few well-known pieces would work if they were switched from past tense to present tense.
"It's a bright cold day in April and the clocks are striking thirteen."
"The thousand injuries of Fortunato I bear as best I can, but now he ventures upon insult and I vow revenge."
"It's the best of times, it's the worst of times, it's the age of wisdom, it's the age of foolishness..."
It's natural for people to want to tell stories in the past tense because it's easier for us to digest them that way.
My advice would be to focus on maintaining consistency in the past tense. You can do that by checking to see that all of your main verbs are in the past tense. (Not all verbs because in English we don't conjugate each and every verb in a sentence no matter which tense we're using.)
"She wanted to go." (Main verb is past tense, secondary verb stays in the present <infinitive>)
When crafting dialogue sometimes the speakers use the present tense in direct speech, but the author might employ the past tense in reported speech.
"She('d) said she wanted to go" or "She said 'I want to go'."
When writing, it's perfectly acceptable to use whichever tense feels more natural because you can always go through it later and fix any errors, but beware that in English, switching from the present to the past or vice versa involves more than just changing a bit of syntax here and there. In some instances, it might entail restructuring whole sentences or paragraphs, so it's definitely best to try to remain consistent as you go.