Paid entrance works great for me. I started with free entry and paid rides at the beggining to nail down at least some basic rides. It is important to consider shops as well, as they can play important role once you make rides free and entry paid. At the beggining, it is a bit rough, but pretty much doable. You just have to cut on expenses for a year or two and it is well worth to invest into some marketing.
I don´t understand people who keep saying it´s unplayable this way, because it is pretty much playable. I´m the proof and many other people did it too.
What kind of entry fee prices are you setting. I'm doing a real world comparison and losing anywhere from $7k to 12k a month in sandbox. Though sandbox doesn't really matter as its unlimited funds to build with.. I like feeling like my park is doing well and making money. I've currently got prices of 42.99 per guest 3 coasters and 7 flat rides among what I consider to be an absolutely beautiful alpine park. averaging about 2500 guests or so...