How to use safely
There are a few simple rules that can help using retinoid products safely (as in without causing too much irritation and damaging the skin barrier):
1. Start slow: it's best to start applying the retinoid product at night, twice per week or every other day (if your skin is not usually sensitive). If there is no adverse reaction & your skin isn't too dry, after 2-4 weeks you can slowly increase the frequency up to once per day.
2. Use a sunscreen daily.
3. Minimize the irritancy risk with the rest of your routine: for example, switch to gentle cleansing once per day (at night) instead of morning & night, go for fragrance free products, do not use peels (e.g. glycolic acid) often - or maybe stop them completely.
4. Use a good gentle fragrance-free moisturizer. If your skin is sensitive, you can apply the moisturuzer before the retinoid product. The retinoid will still be effective, but you are less likely to get a reaction.
5. Pause retinoid if you notice redness, strong dryness, flaking etc. It is not helpful to persist through inflammation caused by irritation - it causes more harm than good to the skin.
A bit more info on using retinoids for sensitive skin here: https://whatsinmyjar.com/entries/93/how-to-start-with-a-retinoid-if-you-have-sensitive-skin