My dear Avis,
That is a challenging question for any citizen of Boldhome to answer, and I do not know your personal circumstances. It is common to aspire to the most prestigious regiment that you can join, particularly if your personal circumstances mean your need for income is pressing. Occasionally a newcomer will aspire to make themselves known about town for a month or two while they build a reputation so that they can enter at a higher rank, thereby sidestepping the weeks of duty required of a private or subaltern provided they can afford the rank of ten-thane and the purchase of a mount.
I have been honoured to serve as Ten-Thane in Goldgotti's Company for a year, earning accolades in battle, but aspire to head to the summer campaign in a new regiment. Many others have served with distinction in Colymar's Cavalry. Of course there would be no shame in joining the Candle Dancers, Free Philosophers or any of the Magical Union Brigade even though they are not presently required on campaign. Training for a few months before seeing action may be a wise choice if you have come to town with enough coin to pay for your board, lodging and entertainments. Mularik's Company has a new Warlord, of whom more great things are expected now he has been ennobled for his brave actions on the battlefield over the winter months, but it may be beyond the reach of an individual who has yet to develop a reputation. I know it was for me when I arrived.
If you do decide to enlist, you will be expected to be a member of a warrior cult, so that will be another decision to make. Orlanth is the most popular and has a grand temple here in Boldhome, but there are several others to choose from.
I wish you every success in your endeavours
Grumbold Rahlefson, (former) Ten-Thane of Goldgotti's Company