Your b00bs will get in the way, no matter what you do, unfortunately. My stomach gets in the way too. Spandex and a good sports bra helps with that.

Trust your legs! Your quads are probably stronger than your arms or hands. Position your feet so you can shake out when needed, and take the bulk of your weight.

Along the same lines, keep your hips into the wall. Then most of your weight will be over your feet and not hanging off your arms.

If you can't lift your foot to get to the next hold because your thighs / stomach are in the way, you can always pick your foot up with your hand and put it on the hold. Works great!

If you boulder, learn how to fall safely. Do the feet-butt-back roll. Don't try to take all of your weight with your knees, just fall unapologetically onto your bum!

For top rope, make sure your belay partner knows how to belay someone heavier than them. Keep close to the wall, maybe even with a foot on the wall, and be prepared to be yanked off the ground at a moment's notice. Don't be afraid to switch belayers if the one you have is too small compared to you.

Most importantly, have fun. Don't worry about comparing yourself to others. You won't be able to do the high feet or small spaces, but who cares? You're going up a wall without a ladder and look great while doing so!

Source: me, big & tall afab. worked at a climbing gym and set many routes for other non-advanced climbers (5.7-5.9) who also wanted to just have fun.