I meaan investments can still work, just that it's a lot better to start ( and do stuff ) on your own since you're able to optimize the business to possibly generate the maximum profits that you can. Personally I'd go for self development first but if what your business is has a sort of free platform to help you (like fb is to ecommerce) then I reckon doing that immediately would work.

Though I guess if you start investing in yourself, both learning wise and skill wise that would be pretty much two birds in one stone.