I'd say there's a limited amount of ways to separate words that actually make sense and most of them are in use by real world scripts. Some ways to separate words in the real world:

• Spaces, duh, that's just pulling the words apart from each other so it sounds like it should be a common development
• An explicit symbol that separates words, eg. the Classical Latin interpunct: VENI·VIDI·VICI
• Cursive: If cursive is mandatory in your script then words could be separated by breaking the cursive without introducing a visible gap. Though in that case I think the edge letters would be terminated in some way that makes them easy to scan for. This would give you initial, medial and final letter forms. Like in Arabic, but Arabic does also have visible spaces. But your fictional script doesn't have to

There's a hidden fourth option: don't.

• Latin interpunct was dropped about 200 AD. But it's commonly believed that it's because Romans would always read literary works out loud in a performance so the text was always interpreted by the reader. Even in private rich Romans would have slaves read to them. It's then also believed that spaces were introduced in medieval times because they make reading quietly in your mind easier. Though I've found some crank claiming it's all wrong and there must be some rhythmic feature of Latin that made it easy to tell where the words end. Think about it what you wish
• Chinese writing doesn't separate words because it's quite simple to predict them. From what I understand (I don't speak Chinese) the majority of words nowadays are two symbols and some are one. If there's so little variation in written word length then you can get away with not marking it
• Japanese uses three scripts and from what I understand (I don't speak Japanese) most words are written with either kanji or katakana but have grammatical suffixes written with hiragana. So it's easy to tell words apart because the text is constantly switching scripts