I am new to the trombone and I need to know what I need to do for maintenance to keep it in good condition. Thanx for any advice

Good question!
1. use a trombone stand or when you're not playing rest the trombone with the bell on your lap. The point is to not put weight on the slide. Ever.
2. If you must set the horn on the floor, there should be three points contacted with the floor. The tuning crook, the mouthpiece, and the bell. The slide will point slightly upwards at about a 25 degree angle.
3. Don't use a cleaning rod on the inner slide. Use a snake. A rod can damage your leadpipe.
4. when cleaning outer slides with a rod, hold the slide by the tube that is getting cleaned. don't force it.
5. clean your slide often. build up is the most common cause of slow slides
6. Know what a good slide is capable of. Most kids I have seen have horrible slides and don't even realize just how much better they can be.
7. Avoid gig bags if possible.
8. Use good slide technique ... the better it is, the less stress you'll put on your slide.
There is a good article from the slide doctor for testing and cleaning your slide. This should help.
http://www.slidedr.com/sickslide.htm
6. as for slide lubricant... no matter what you use, people almost always use too much. This is especially true for users of superslick or trombotine.
7. if you slide becomes dinged, or out of alignment, take it to the shop or send it to the Slide Doctor. Continued use of a slide that is in bad repair only makes it worse and damages the inner slide plating.

When I gave my trombone a bath a couple weeks ago, the un-filtered tap water made smuges on the bell and slide. If you can, use a filter to take out the minerals and chlorine in the water, or use Sparklets or some other bottled water (although it takes a lot). If you can't do that, you can just wipe of your trombone with a damp cloth (use filtered or bottled water for this).

When I gave my trombone a bath a couple weeks ago, the un-filtered tap water made smuges on the bell and slide. If you can, use a filter to take out the minerals and chlorine in the water, or use Sparklets or some other bottled water (although it takes a lot). If you can't do that, you can just wipe of your trombone with a damp cloth (use filtered or bottled water for this).

When I gave my trombone a bath a couple weeks ago, the un-filtered tap water made smuges on the bell and slide. If you can, use a filter to take out the minerals and chlorine in the water, or use Sparklets or some other bottled water (although it takes a lot). If you can't do that, you can just wipe of your trombone with a damp cloth (use filtered or bottled water for this).

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Sorry for the extra posts. When I first tried to post it said "internal server error" so I tried two more times. I guess it didn't have any problem.

or just dry it with a soft cloth and swab it out with a swab...thats what I do. and send the horn off to a professional cleaner once in awhile...but what steve said was the best.