Trimming Nails

If I have scratching posts all over the house that my kitty willingly uses...do I have to still trim her nails?

That's really up to you. Cats scratch things to sharpen their claws and leave their scent, not to keep nails short. If you don't find it to be problematic and your cats are fine, you may not see it necessary to trim. Our cats will sometimes get their claws stuck in toys or posts, and we like to minimize damage from scratches (on us) or from claws in materials when kneading, so we trim.

I still trim the claws because the scratching post doesn't really keep them from growing.  It helps to get rid of the sheath and with sharpening but doesn't trim back the length.  They also provide a place that kitties can mark which is another reason for clawing.  Clawing also provides a stretching exercise.

I don't know if kitties claws can grow into the pads like a dogs claws can.  I have noticed when they get long the kitties claws start getting caught on things which means damage to furniture and rugs.

Ok...good to know. I think she's going to hate it

Most cats don't like it. Work your way up to trimming by getting her used to being restrained and having her paws touched, and offer rewards for each step of the process.

http://www.thecatsite.com/a/how-to-best-take-care-of-cat-claws

Great idea...she's a pretty strong willed kitty. If she's determined to get her way, she'll take a swipe at you or try to bite. She's four months old...we are redirecting, I hope it stops as she matures

I like to try and trim her nails around once a month, though sometimes it goes longer. It will definitely become problematic when she starts to stick to rugs or furniture....or ME when she's being held or stretching up my long legs while I'm preparing her wet food   It's adorable, but ends up hurting!

When I got her when she was 8wks old I started squeezing her paws and touching them every day until she got used to it, and now usually I can pin her while she's sitting on the couch stool or just plop her down on a soft surface, and after some initial wiggling, she let's me trim them. I only do her front paws. Of course, usually by the 9th or 10th nail she begins to wiggle again, but giving some cheese flavored treats afterwards helps reinforce the procedure

Good to know! A little piece of bacon should do it lol

I trim Xena's kitten nails weekly. She has gotten used to it and doesn't fight- but she did at first. I have lots of posts too, but I don't like sharp kitty claws.

Both Mollipop and Tabby get theirs claws trimmed on the first Sunday afternoon of every month; that seems to be enough for them. Tabby is so used to us doing things to her as we cleaned her ears out and trimmed claws from the time she was a wee kitten (she had a nasty case of earmites when she first came to us and we had to clean her ears out twice a day for months). Tabby lays in my arms patiently while Rick trims claws and cleans ears. Mollipop, on the other hand, squirms and screams, telling everybody within earshot what mean parents we are. It's terrible and we're all so glad when Molli is finished for the month. My t-shirts have little holes in them from Molli's claws.

When we're finished with the trimming and cleaning, off everybody goes to the kitchen for a treat.

Mollipop is a horizontal scratcher and we keep scratching pads and such on the floor for her to use, but she'll still scratch at the carpet every chance she gets. Tabby is a vertical scratcher  and she loves to use the sisal rope on the legs to the cat tree, but she'll still go to the couch. We hiss at them and they stop (for the most part).

If you see her claws getting caught in blankets or pillows or on your clothing, you probably should trim. Toward that last week going into the first Sunday when it's getting close to trimming time, Mollipop tends to get her claws caught in everything....sometimes I inadvertently hurt her trying to get them back out, especially when she's attached to me! It hurts! Last time, I was on the computer and she jumped into my lap. She goes from my lap to over my right shoulder and then to her pillow over by the window. Well, she got caught on the back of my t-shirt and I couldn't get her without really hurting her. I called to Rick and he came over and got us un-stuck. So if your kitty has some "sticking" problems, it's a good idea to trim.

My cats love their scratchers, but they don't keep nails cut short, so I trim nails every other week or every 3 weeks.

Good advice already here.  The claws can eventually curl round and curl in to the paw, but more risk I suspect of your cat being injured due to claws getting caught in other things before that happens - and injury to you if they are very long and sharpened on those scratching posts.  I have told this story before but despite regular claw clipping one of my previous cats managed to pull one of her own claws out at the root when she got startled and ran out of my sitting room.  One of her back claws got caught in the carpet as she turned to race out of the door and claw stayed there while she ran off to the kitchen.  She left a trail of blood behind her, poor baby.  One emergency vet visit, cleaning up of wound and paw in bandages for about a week until the risk of infection passed and she was more comfortable.

@pinkdagger  has given a useful link above, and suggestion to start by gently touching and handling her feat is also a good ploy in my experience.  Try doing this first when your cat is reasonably calm (for a 4 month old) and offer rewards if it is tollerated well so it becomes a positive association.  If you can do this without restraining and work up to holding the leg so you can look at the individual toes.  It takes time but if you can do this it really pays off as you may find you can trim at least some of the claws without a restraining hold and your cat remaining quite relaxed.  With many cats it is the restraint they hate as much as the paw being held and claw clipped:  my cat that declawed herself was one of those and I could clip her claws with her laying on the sofa but she'd fight like crasy if I tried to do it in a hold.

Get used to looking at the claw and seeing clearly where the quick is too so you know where to clip safely without causing pain and risk of infection.  This too will help as you are less likely to cut a claw too far down and cause a lot of pain.

If you have to get a restraint hold on your cat to clip claws try to use one which uses large bady / limb surfaces rather than a hand hold as it will be a stronger and firmer hold for you and more gentle for the cat as no gripping involved.  E.g. use your full arm length against your cat's side and pull in towards your body while sitting somewhere you can move freely, that way your cat is held by your lap, body and full arm and not just a gripping hand, or two which will feel like agression and cause fear.  If your cat struggles or wriggles you will have a firmer hold and be able to manoeuver better to keep your hold.  It also means you have both hands free so one to hold the paw you are going to clip and the other for the clippers!  The other alternative is the pin down mentioned by thesighrye, with cat laying on its front and using your upper body and an arm to hold in to a firm surface gently and clip the front paws by stretching the front legs and paws out to work on. It is quite a good position to get in to if your cat is relaxed on the floor and maybe even do one claw at a time so the experience is very brief.  Just remember which claws you have clipped for the next day when you go to do the next one.  Which ever method,  plan out where your hands and arms are in relation to teeth so you are best protected against any attempted bites if these are expected.

With Mouse I usually go for the laying on his back on my lap like a baby as described by  Winchester, except he wriggles like crazy to start with and makes himself as looooong as he possibly can so it's difficult for me to get him in to the position where I have a good strong hold on him (and of course threatens to bite) - at which point he gives in and lets me do my stuff.  Then he leaps up and runs off to his fish snack tin with a look of anticipation!