Personally I find it very important even when I study how to read without vowels to still look up every new word with vowels, to be sure I know how to pronounce it right.
If the expanded spelling without the vowels is different than the spelling with the nikud (vowels), I write the word in my word book both ways to be sure I know how to spell it properly when I write a text, because normally Hebrew is written without vowels.
This is important because some words when written without nikud require the expanded spelling, like for example
to study/learn lilmod ללמוד (expanded spelling)
to teach lelamed ללמד
otherwise they would both look the same and it would be hard to tell what the person is saying.
At the beginning, when I did not have a sense of how the plural vowels worked for nouns, and the feminine forms for adjectives, I always looked them up in my paper dictionary and wrote in my book. This is not possible with most online dictionaries, but in my paper dictionary it has the plurals for nouns and feminines for adjectives as well. This is important I believe, especially because the vowels at the beginning of a word as well often change and because many nouns have irregular plurals.
Example for a noun: place - makom mekomot מקום מקומות
The vowel changes from a to e, and also it has an irregular plural ending for a masculine word (the usual ending is 'im', not 'ot')
Example for an adjective: young - tza'ir tze'ira tze'irim צעיר צעירה צעירים
The vowel changes from a to e
Each person learns differently, but for me that is what works the best. I find it is better to put a more serious effort at the beginning and learn properly than to have to unlearn and re-learn later.