To minimize getting declined:

• Check their wishlists
  • do you have something they want?
  • does what you're offering match their taste?

You don't want to be flaked on, so:

• Check their feedback & ratings
  • do they have a good track record?

Don't get stuck with something you don't want:

• Ask questions
• Agree on the swap terms before sending
  • If not, say you've changed your mind
• Don't get shortchanged: barter

Keep it friendly:

• Don't forget to rate your partner
• Send a thank you note