For seed starting I'd leave top soil out of the mix. In general I'd leave top soil out of plants in pots. Better use a potting mix.

Thanks

I agree with subtrop.

For growing plants, I'm a big fan of mixing potting soil with perlite (typically 50:50). This is especially true for plants that like to be constantly moist, but not soggy (for example Tacsonias).

I prefer to control how much fertilizer I add to soil, and don't use Miracle Grow soil, perlite, etc. partly for this reason. I do use MG fertilizer, though.