Samus's Power Suit is her most vital asset. It's not just armor; it's a modular system that integrates all her abilities and weapons. As you find Chozo artifacts and technology, the suit gains new functions.
Think of your 'build' as the collection of upgrades you've found. A Samus with the Space Jump, Screw Attack, and a full complement of Energy Tanks and Missile Expansions is a far more formidable force than one without. Prioritize finding these upgrades to maximize Samus's potential and make the game significantly easier.