Reverse the reading direction
A label has a front that sells and a back that informs. Starting at the front means reading the claim before the facts. Starting at the back means having the facts before the claim takes effect.
The sensible order is: directions, amount table, ingredient list, warnings, storage, responsible business, batch and best-before date.
Steps one to three
First the directions: they define the reference unit for everything else. If they say two capsules daily, every per-serving figure refers to two capsules.
Second the amount table: check whether a column means per capsule or per daily serving. Third the ingredient list: it is ordered by descending weight, so anything late in the list is present in small amounts.
Steps four to six
Fourth, warnings and excluded groups plus the mandatory statement that a supplement is not a substitute for a balanced diet. Fifth, the responsible business with a real postal address.
Sixth, batch number and best-before date. You need both for a query or a recall, so note them while you use the product.
Comparing two products
Complete these six points for both products before looking at price. In most cases the decision is already made by then, because one product either states more or leaves something out.
Add two numbers: active amount per day and price per day. Only those two make different pack sizes comparable.