First, ask yourself how much of each you wish to do. Ideally you'd want to lift 2-3 times a week and get cardio 3-4 times a week for 6 exercise days, with 1 day 'off'.
Then work out where you can lift. If you have a gym membership you'll want to go there - but can you go any old day or does your routine mean you can only go on Thur-Sun or something?
Then ensure your ST is at least every alternating day, not two days in a row.
Then fit the cardio on the days between.
Deb, in New Zealand