1. According to Avot 2:2, all Torah and no work will end up being worth nothing. Same with all work and no Torah. So the ideal is clearly to work part-time, enough to support yourself but to give yourself time to devote to Torah and mitzvot.
2. Some professions demand long hours, while others are more flexible and are easier to do part-time. Consider acquiring a skill that will allow you to be an independent contractor or start your own practice. I know someone who learned how to hang wallpaper in three days and then went on to be his own boss and work whatever hours he wanted for several decades, making a decent living. A lot of things probably fall into this category –web design, plumbing, doulas, etc.
3. Working with secular Jews and gentiles presents tremendous opportunities for Kiddush Hashem. Most secular Jews don’t think very highly of frum Jews, and many gentiles are especially anti-Semitic when it comes to the Orthodox. If you do a good job and smile (see Avot again!), people will begin to look more fondly on frum Jews and Torah Judaism in general. If you spend enough time with secular Jews, you may end up being the main factor influencing a secular Jew to make teshuvah.
4. Check out this quote by Rabbi Pinchas Eliyahu Horowitz of Vilna (Sefer HaBris):
Also, such a person can be confident that he will not miss even a single day of his service of G-d, since his means of support is always at hand, and his sustenance is available in his dwelling and his own city. He will not lie down at night without having eaten, because a tradesman is never without sustenance, nor will he need to travel to faraway places in other lands to seek his sustenance. For when travelling, by necessity a person must be neglectful of the service of G-d, as is well known; there is no way to turn aside and focus on Torah and prayer with concentration when one is away from his place and has set out on the road.
[work and Torah learning]
[of Torah]