Two things:
1. Don't know if this is now 'old-news' (if so, apologies) but my Asthma Clinic Nurse introduced me to the Tidal Technique yesterday.
Apparently it delivers a 'much' higher dosage to lungs (something like 25% higher) than other techniques with / without a Spacer.
The Technique involves using a Spacer BUT in a particular way.
As usual you shake-up your inhaler, attach to Spacer then, once you've breathed out a bit and positioned the mouthpiece, you discharge just one shot into the Spacer, then slowly breath 'in and out gently' - but 'several' times - over twenty to thirty seconds (rather than taking a single big inhalation).
If your prescribed dose is two puffs, you wait a few minutes and then repeat the process. (Don't do two puffs in one go, apparently).
2. If Chest Sputum is one of your issues, something that helps me, is to to take just one puff, then wait for a full hour or so before repeating - I'll explain why I believe this can help. A layer of sputum / mucus covers the airway lining and is a barrier to inhaled drugs trying to reach the lining. About an hour or so after the first dose, folk who have sputum / mucus to contend with, frequently find that the 'first dose' has loosened things up, and they often cough and expel part of that barrier / layer within that first hour. This means that the second dose / puff, then has less of an obstacle to overcome in battling through the sputum layer to reach the airway lining.
None of this should be construed as medical advice (I'm not qualified to give any). You may, however, want to consider these points and / or ask your own Advisor about them.