MOST WEIGHT PROBLEMS BEGIN IN THE KITCHEN. IF YOU ARE HAVING PROBLEMS LOSING WEIGHT AND/OR KEEPING IT OFF, KEEP A FOOD LOG. Sorry for the bolded all-caps sperg there, but seriously, examine your eating habits before you do anything else. A good metric for how many calories you should be eating
while maintaining an active lifestyle is to add another 0 to your weight. So if you're 250 lbs, eat 2500 calories, and make sure about 40% of that is protein.
Lift weights. Compound exercises involving free weights are superior to using machines because they engage multiple muscle groups at once. Not only is this more effective, but you'll spend less time in the gym. (That said, machines are usually fine, but watch out for ones that isolate your joints, and stay off the goddamn leg press if you don't know how to do a proper squat.) Good resource:
exrx.net. Good starter routine:
Sean10mm's modified Starting Strength.
Do cardio, but try not to do it on days you're lifting weights. Alternating days is usually best so you're making the most out of both your strength and your cardio. If there's no way to do this, it's safer to knock out your cardio
after you've done all your strength training. What kind of cardio and what kind of machine you use doesn't matter, do whatever feels comfortable, but if you're running make sure
you're using the correct form or you run the risk of leg injury. Your maximum heart rate is
220 - your age. If you're just aiming for wellness and not like marathons or whatever, staying between 50% and 80% of your max is your goal.
Drink lots of water. Buy a sport bottle, fill it, suck that bad boy down. Take all day if you need to, just get it in you. Using stuff like Crystal Light to make it less boring is fine. Soft drinks, coffee, milk, beer, iced tea, anything that is
not water does not count as water. This doesn't mean you can't ever have other stuff, it just means that you need to
drink water.
Get off the scale. Don't weigh yourself more than once a month. Take weekly measurements instead. Notice how your clothes start fitting better. Watch how your skin clears up. Pay attention to the lift in your moods. The weight changes will come as you learn to manage your habits. Most people damn themselves by agonizing over the scale.
I'm a lady lifter too, and have been for several years now. I also do a triathalon every other year. I love sperging about this shit. Feel free to bother me with any questions.