It all depends upon your existing content and either you are running a channel / group.
If its group then force invite can be done which is a way to bring up real users at a lot faster than DMs. But if its channel then this approach is not possible.
for channel/group we can use DMs , with dms again results are according to your content, just consider it like TV promos, if you have a good commercial you can get better results. All the guys who do DMs are just carriers to publish your message. Some may be good at what they do than others but end result is your content again.
Forced shilling is bot/human will go to group to group and post your message... not guaranteed deliver but a group which has 100k members if message stay there for 1 hour may be 10k have seen it.
HTH