I assume you mean a B2C web or mobile application of some kind. The main items on your P&L that will dwarf everything else are product development costs (the labor costs of engineering, design, and product management) and customer acquisition.
Customer acquisition is the silent bloodletting of consumer startups. Everyone knows software product development is expensive, but since you specifically mentioned "Consumer" it seems prudent to point out that most consumer products require a massive volume of adoption and continued usage to be profitable. The most likely models are SaaS (some kind of utility usually, like an Evernote), a marketplace (buyers and sellers in a vertical that has low efficiency transactions that software could improve), or a media play (like FB, etc., where the user is the product, and the model is ads). Any of these will require A LOT of users in order to get traction. That's got to be your focus.
If you're considering getting into a consumer web play, your team will need to iterate many times on your prototype or MVP to be sure you have hit something consumers really want before you invest in building a full-blown platform. You will simultaneously need to explore novel and standard tactics for attracting new users, and you'll need to do it very quickly. You'll need a team that is fast, nimble, and experienced.
Wherever you operate, your best bet is to assemble a co-located, cross-functional, dedicated team for this. Don't skimp on UX or speed of iteration. You can afford that in enterprise software, but consumers are ruthless. A team that's all together in one place will be best enabled to kick ass on this kind of challenge.