When buying scuba gear, there are four things to consider: fit, features, care/maintenance and price. Good scuba gear isn't cheap but, while wetsuits have to be replaced once in a while, the hard gear like regulators will last essentially forever with good maintenance. It's worth investing some time in choosing well.
Fit is first and foremost. A wetsuit that doesn't fit well won't give you the thermal protection you expect and might even constrict your breathing. If it isn't flexible, you'll feel cramped and constrained underwater. (Drysuits are generally made to be loose.) A regulator hose that's too short will have you twisting your head and a mouthpiece that doesn't fit will cramp your jaw muscles. Try on gear before you buy it. Most gear comes in a variety of sizes and BCs come in women's and men's versions. Your local dive shop can help you get the right fit.
Equipment manufacturers make gear with a wide range of features from basic and serviceable to state-of-the-art (and priced accordingly). This is a good area for online research. Keep in mind three things.
As for care and maintenance, the first thing to look at is what kind of warranty the product comes with. How often does the manufacturer recommend it be serviced? Can some of the maintenance be done by the customer (e.g., changing batteries)? Are there any special care instructions?
And finally, everybody's favorite topic: price. Because the gear will last a long time (even wetsuits), if it's not right for you it doesn't matter how cheap it is. Make sure that you've found something that will be of good use to you (fit, features, maintenance) and then look for the best price you can find. And don't automatically assume that you can do better online. Because of the kind of incentives manufacturers give to dive shops, your local shop will often be able to beat the online price, especially if you're looking at packages. At least check it out before you buy.