Annti, congratulations on your purchase. I remember your earlier posts about getting a horn. I hate sticky, sluggish valves. Those cheaper beginner horns seem to have inconsistent valve action. It seems you got a good deal with your Yamaha trumpet. Hopefully, it was cleaned. If I remember correctly, it is used. Buy a snake brush and a mouthpiece brush and make sure the leadpipe is clean. You are probably using the mouthpiece that you used to play the leadpipe. Mouthpieces should be cleaned often. I like a cleaning product called Spitballs. You can get them from Amazon or music stores. (Herco HE185 Spitballs)

Have fun,
Ronald Carson