2. Tune the 2nd valve on 3rd line B natural.
3. Tune 1st valve on Bb 3rd line.
4. Do not tune 1-2 combinations. They will be slightly sharp. Using 3rd valve is a common way to tune any notes where 1-2 would be used.
5. Tune 3rd on A natural. Ab and other 2-3 combinations will be slightly sharp.
6. Repeat steps 1 through 5 on the F side. Do not move the main tuning slide. Use the F slide(usually the one nearest the bell). There other slides which can tune either side of the horn. Consider these "slides of last resort" and are primarily water slides.
7. The intonation on the Bb horn(thumb down) is generally better than the F horn (or at least matches other Bb brass instruments better).
8. Tone color/projection consideratons are a topic for another article and I know there are many different opinions on this. Would like to start a discussion on that!