How do I start in bash when ssh'ing into my server?

As a regular user, you can change your default login shell using the chsh command. Here is an example:

chsh -s /bin/bash

Another option is to use usermod as root:

usermod -s /bin/bash username

For the case where you're trying to use a shared account (for whatever reason) and can't change the default shell, then you can run

ssh -t <user@hostname> bash -l

If you need to keep your environment from some other shell, then you can run that shell first; for example

ssh -t <user@hostname> ksh -c bash -l

You edit /etc/passwd where the last entry is the default shell. Make it /bin/bash.

Alternatively, you could alter alter the system default of /bin/sh not being bash.