I have kept a mosteras for many decades. A few basics. The brown spots on the edges are usually too much water (causes N deficiency), salt buildup, or lack of fertilizer.

Watering, the pot should be saturated then allowed to completely dry out. Don't pay attention to the soil, look at the leaves. When the plant is drought stressed they have a slight dimpled look. The leaves appear duller and not as shiney. Salts- the are very sensitive to water softeners. Do not use water that has been softened.

Fertilizer - they do best with slow release fertilizers. For conventional fertilizer you want polymer coated. For organic you want manures aka something that takes time to break down.

Salt leaching- you need to leach the pots at least every couple of years. The smaller the pot the more often it is needed. Flushing a bunch of water through the soil removes salt buildup.

Pot size- ignore everything anyone says about pot size for monsteras. They always get rootbound in any pot but they don't care. You can grow giant ones in a 1 gallon pot. A larger pot = less frequent watering and fertilizing. For most of my plants life I kept it in an 2 gallon pot for ease in transport.

Light: monsteras are tree climbers. In low light conditions they grow away from the light looking for a tree trunk (small leaves with long internodes. If you want big beautiful leaves, they need 4-5 hours of direct sunlight. Preferably in the early morning or evening.